Plots and IJulia format issues

Hello,
the following MWE of a julia-jupyter notebook (rename to .ipynb) shows a problem with plots:
MWE1.ipynb.jl (224.5 KB)
no matter the selected output format, the cell outputs an “image/png”, “image/svg+xml” and “text/html” (both latter containing the svg, see attached file source). This is first of all unexpected, as fmt should set the output format for jupyter/Ijulia according to here. Further ist leads to problems as jupyter nbconvert --to-markdown fails to include links to the supportfiles (like ![svg](img.png)) and just prints the svg from “text/html” as plain text into the markdown file.
Rename to .md and see here:
MWE1.md.jl (75.9 KB)
Where is the problem here? is it Plots.jl or IJulia?