Humpf. I got one glorious all red plot the first time I tried. Now I get one red bar and the rest white with either c or color.
What versions are you using?
(dfenv) pkg> st
Status `~/Desktop/Julia/dfenv/Project.toml`
[336ed68f] CSV v0.10.4
[a93c6f00] DataFrames v1.3.4
[ccf2f8ad] PlotThemes v3.0.0
[91a5bcdd] Plots v1.29.0