The same Problem here…Cubase 12 does NOT SCAN
C:\Program Files\Common Files\VST3 !
The only VST3 Folder scanned is
C:\Program Files\Steinberg\Cubase 12\VST3
So I created a new folder in
C:\Program Files\Steinberg\Cubase 12\VST3
and made a symlink to
C:\Program Files\Common Files\VST3
Now it works. For all: Search for a program called JunctionMaster Pro by Bitsum (can’t post links here), with it you can make symlinks.