I have always used F11 as a shortcut to open the list of instruments. It is also clearly labeled under the studio menu VST Instruments (F11). Cubase 14 this is the only shortcut that I know of that do not work. It is the same behavior in Cubase 15.
I assume you already opened key commands and made sure it’s still assigned?
Also in key commands window if you click the little keyboard icon top left and then hit the shortcut it should jump to the assigned command in the list…..if it doesn’t then it suggests your keyboard (or the o/s) is not sending it (or is blocking it)
Once you’ve followed the steps outlined by Grim. If you see that your key command is indeed assigned and still not working; the most likely culprit will be something else on your system that is grabbing that key. Some other app that works from a hot key. Screen capture, or some other tool possibly.
I dunno. It says even on the menu that F11 is assigned. I double checked the key command. It must be something from the logitech keyboard and the mac that blocks just F11 because F3, F4, F12 etc etc. they all work just like expected.