R 20b3
OS 15.5b4
MBA M4 32gb
open up Prefs>system>Audio Plugins
click on the category area to set category item for individual plugin
menu which should draw just to the right of the mouse click, instead draws in the top right of screen

yes you can mouse over to it and select an appropriate item... but it should be a bit closer.
ideally R would read the category of the VST3 / AU and autofill most catagories on its own...
S