If the above doesn’t help as you have no “Switch to plug-in editor” option on your windows, then there was some discussion on this a while back, see here:
Hi, I replicated the problem by renaming the file AudioPlugs.srf inside the C:\Program Files\Steinberg\Cubase 12\VST3\Cubase Plug-in Set.vst3\Contents\Resources folder , i.e. making it “invisible” to Cubase.
Now, if this file exists there, it may be corrupted, and if it doesn’t, this is the expected behaviour (no plugin editor switch menuItem).
In either case, you probably have to get a fresh copy of this file from a friend. I would post it here, but it’s around 100mb. Note that simply re-inst…