Why is this Plots.jl contour plot blank?

I’m trying to produce a “pork chop” plot for an aerospace engineering assignment. I’m using Plots.jl, and the GR backend.

I want to plot a contour plot, with \Delta v as the “z” axis. For some reason, I can plot the data as a surface, but the contour plot shows up blank. Has anyone else ran into this?

using Plots

MST = [2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4579665e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580165e6, 2.4580665e6, 2.4580665e6, 2.4580665e6, 2.4580665e6, 2.4580665e6, 2.4580665e6, 2.4580665e6, 2.4580665e6, 2.4580665e6, 2.4580665e6, 2.4580665e6, 2.4580665e6, 2.4580665e6, 2.4580665e6, 2.4580665e6, 2.4580665e6, 2.4580665e6, 2.4580665e6, 2.4580665e6, 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TOF = [100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 650.0, 700.0, 750.0, 800.0, 850.0, 900.0, 950.0, 1000.0, 1050.0, 1100.0, 1150.0, 1200.0, 1250.0, 1300.0, 1350.0, 1400.0, 1450.0, 1500.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 650.0, 700.0, 750.0, 800.0, 850.0, 900.0, 950.0, 1000.0, 1050.0, 1100.0, 1150.0, 1200.0, 1250.0, 1300.0, 1350.0, 1400.0, 1450.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 650.0, 700.0, 750.0, 800.0, 850.0, 900.0, 950.0, 1000.0, 1050.0, 1100.0, 1150.0, 1200.0, 1250.0, 1300.0, 1350.0, 1400.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 650.0, 700.0, 750.0, 800.0, 850.0, 900.0, 950.0, 1000.0, 1050.0, 1100.0, 1150.0, 1200.0, 1250.0, 1300.0, 1350.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 650.0, 700.0, 750.0, 800.0, 850.0, 900.0, 950.0, 1000.0, 1050.0, 1100.0, 1150.0, 1200.0, 1250.0, 1300.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 650.0, 700.0, 750.0, 800.0, 850.0, 900.0, 950.0, 1000.0, 1050.0, 1100.0, 1150.0, 1200.0, 1250.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 650.0, 700.0, 750.0, 800.0, 850.0, 900.0, 950.0, 1000.0, 1050.0, 1100.0, 1150.0, 1200.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 650.0, 700.0, 750.0, 800.0, 850.0, 900.0, 950.0, 1000.0, 1050.0, 1100.0, 1150.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 650.0, 700.0, 750.0, 800.0, 850.0, 900.0, 950.0, 1000.0, 1050.0, 1100.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 650.0, 700.0, 750.0, 800.0, 850.0, 900.0, 950.0, 1000.0, 1050.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 650.0, 700.0, 750.0, 800.0, 850.0, 900.0, 950.0, 1000.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 650.0, 700.0, 750.0, 800.0, 850.0, 900.0, 950.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 650.0, 700.0, 750.0, 800.0, 850.0, 900.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 650.0, 700.0, 750.0, 800.0, 850.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 650.0, 700.0, 750.0, 800.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 650.0, 700.0, 750.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 650.0, 700.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 650.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 600.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 550.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 500.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 450.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 400.0, 100.0, 150.0, 200.0, 250.0, 300.0, 350.0, 100.0, 150.0, 200.0, 250.0, 300.0, 100.0, 150.0, 200.0, 250.0, 100.0, 150.0, 200.0, 100.0, 150.0, 100.0]
ΔV  = [57.12796017064814, 86.6677829175468, 100.64508325897926, 100.66192549425003, 99.38927630310889, 97.7351260203709, 94.98702474974323, 88.02900884137702, 73.1565105972919, 57.16468363086139, 50.03501091798979, 73.39484911403636, 100.60655159711814, 102.19449229015507, 101.27844056463192, 100.30465871525043, 99.19950795669246, 96.10843612412553, 86.1712161283431, 70.87674041934233, 59.49158570346219, 66.01972153702758, 99.91655393284326, 104.31833444322535, 103.1917817262299, 101.94576769286483, 100.98071838928203, 99.33584573999131, 92.93679426842561, 46.756997832143256, 35.09771934976893, 67.92963236373575, 104.89897626286387, 106.69475397593854, 107.1615684145086, 103.01108067293656, 88.58324416662913, 70.32474191174447, 55.92723801839764, 46.08038597194688, 40.83476509167221, 50.57714857823702, 104.91969177277653, 107.98366837615178, 109.27442192340712, 108.7172600819055, 100.20036262823687, 84.17036356501674, 69.2701802666228, 58.0307556531828, 50.383865613463264, 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24.87112493842804, 24.896672043508843, 37.94360145915025, 90.1532313908677, 102.95880349072226, 104.42216381637328, 104.93318425959148, 102.82405137959404, 92.3759251957175, 75.19414549835221, 60.28412219524678, 50.3865348002942, 48.00593117892994, 77.74957509046233, 104.63155897251308, 106.15610890397716, 106.7504783226848, 106.53526810000146, 100.87616416714289, 47.822666017586236, 33.479775064909376, 25.95850588011139, 21.43730432182543, 18.40250223414825, 16.01564917374557, 107.56728119209683, 112.71402255481043, 114.30169794675344, 106.44562280961168, 89.49263508760367, 73.30360676754769, 60.718535672973886, 51.04158417188622, 43.364556130091245, 36.9732639237946, 31.560745809757723, 113.81800140679279, 116.46430675771244, 113.33150627710162, 53.591309254095506, 41.443596886393784, 34.35105722297754, 29.56389200624264, 26.286259881879815, 25.311697195314526, 47.697158081407295, 120.21498509057884, 117.77738404420843, 102.76992779246312, 87.03370333717143, 74.26736152364255, 64.12220129190338, 55.86019320710017, 48.96762141356082, 43.3988720174068, 43.88104585335325, 117.80823703890286, 123.09116687601342, 68.0880097359415, 54.778896548691684, 46.97743495036504, 41.434897166965875, 37.294415767913385, 35.1982007718779, 55.02198677775101, 124.51575433296416, 113.03152639747624, 98.9695520677256, 87.16493989169697, 77.55931081985199, 69.56041976557444, 62.708671321997244, 56.729788417251925, 51.72254172896499, 52.03642234631417, 126.80056123115361, 85.81274842231666, 69.66794652221928, 60.572301475307185, 53.874180261929304, 48.117198494436, 42.7361164469778, 66.27498625186931, 119.18443717375995, 107.38974381279948, 97.37241676420444, 89.13554459074241, 82.16559015667546, 76.04899962857046, 70.47661746989445, 65.15737095587713, 59.62646019906577, 55.24048007392827, 102.07137278790285, 83.32651682403667, 73.23435539595015, 65.33398033847567, 56.71175046729205, 44.91203827633524, 87.498691175166, 111.03602710328552, 103.74816823922676, 97.56635303473168, 92.3128567774802, 87.6642598644038, 83.3401714965592, 78.98104017477715, 73.65233071508261, 64.7659545891131, 114.04131345013009, 94.51971239598205, 84.20897238678258, 74.07535386155904, 59.2405567025749, 44.412165474474314, 58.85336802398223, 101.12424656688228, 101.65989828359906, 99.17527678024281, 96.6685091705854, 94.29735374542477, 91.79366203071824, 88.01711406118537, 79.43424468911162, 121.14191058128503, 103.53244854778936, 92.50415872484143, 75.91184027055033, 56.32810996787382, 42.81878724204186, 39.136053211335124, 59.419343002621225, 97.73750827132602, 102.32789141106093, 102.72929162585528, 102.6912249752387, 101.34772428256301, 94.1903284521765, 124.97101211683518, 110.35537059334531, 93.80047890402348, 72.03448045993524, 54.56538343767609, 42.718116693867316, 34.82833216419907, 29.780050876462337, 29.460280914705066, 108.2616494159985, 110.85412928985363, 112.4803065377584, 107.86901245271817, 127.2205472460058, 110.98068122419127, 89.37491214816325, 70.6017108376069, 56.961680751434415, 47.08559811057257, 39.681048824447345, 33.97941931208506, 30.193259919383053, 49.91137038199041, 118.7601374668738, 118.96437466396752, 126.94820675908693, 106.02341791165082, 87.60640295828892, 73.65371535581666, 63.137314097426604, 54.95397548920828, 48.387834753157016, 43.10796500613593, 39.73310498867852, 54.176402724598034, 125.32040617002683, 122.54046337642187, 103.33122927926433, 89.81214652302405, 79.54873364307615, 71.32142710337624, 64.41009699183367, 58.36297446692978, 52.89027722733086, 48.059198325568886, 63.89158160741205, 119.83231590649974, 103.94404642461302, 93.99738524146635, 86.40495585881773, 80.00062996826053, 74.18454527533189, 68.44703982627748, 61.89157598416027, 52.52398910663996, 118.6377847759437, 105.6608386001364, 98.51342238048522, 93.25645744192964, 88.66879170896163, 83.98233376994949, 77.84571072379055, 67.18938682276307, 108.81748675966179, 106.35655313264142, 102.83295057388045, 100.24489169890892, 97.74489168073332, 93.56798509442577, 83.29275498789814, 65.01966387205287, 89.91415601748552, 107.7148098599803, 108.07751178008033, 107.16540077538541, 99.17328716277297, 48.585926148032016, 25.14807290810767, 103.64671613082584, 116.05268501718031, 112.69866454112751, 30.451716576992965, 20.052116259608802, 79.98175036528436, 121.1865107356042, 17.465918760085252, 19.4548077075399, 104.94675899046614, 15.368058279399282, 15.228936793618315, 16.736956830711787]

plot(
    surface(MST, TOF, ΔV), # correct plot
    contour(MST, TOF, ΔV)  # blank plot
)

Plots contour does not seem to like input x y vectors (MFT, TOF) which are not sorted and have repeated values.
Thereafter, in order to contour x y z vectors, z might have to be defined as a matrix of values over x y support.