I had some VST3 in a d:\Program Files\Common Files\VST3 folder which was not scanned by Cubase even I added it in the VST manager … ?
Could you add a screenshot of your VST plug-in Manager, when VST 2 Plug-in Path Settings is enabled, in the window, please? Did you let Cubase to rescan the plug-ins once you added the folder?
I made a hardlink via windows console from C:\Program Files\Common Files\VST3 to D:\VST3 and that solved all my problems
You could also make an alias/link at your C drive to your D VST folder.