version 3.20 does not load genres correctly. i reinstalled version 3.19 and all ok.
I don't have any difficulties.
So could you explain with more details what you have done and how you noticed the behaviour?
I am sending an animated gif. better than words.
Check the settings for the display of genres in the tag panel:
See Ctrl+O > Tag-Panel>Genre>Manage...
Please follow the path that I described:
or have a look at