Odd issue here. I had a licensing problem with I Lok for a reverb plugin
MG3 excluded this VST3 plugin after a few attempts to load it.
The issue has been solved with I lok, but now MG3 fails to see the .dll file after numerous rescans.
In my DAW (Cakewalk) I had to reset the plugins for the DAW to load and recognize the .dll file.
Is there a way to do the same with MG3?
Did you try resetting and rescanning MG3’s plug-in database?