To be clear:
The highlight and customized commands still work on Marvin. Apple made a change to their “long press” or “hard press” functionality to put their own options in a sub menu. Marvin already had that submenu filled out with the highlighting, annotating, deep dive, etc. so Marvin’s options got shoved to the side… they are still there, you just have to scroll a bit. The other problem is that Marvin had a dark background with light lettering for the submenu, while apple forced a light background with dark lettering… that makes it hard to see Marvin’s options
If anyone can figure out how to change the submenu colors and/or turn off apples forced submenu that would be good info to have here.