I had a problem with Cubase 12 crashing. It would open only with vst3s disabled. So then I took all the vst3 s out, and loaded them back one by one, reopening cubase each time. They all loaded fine, but when I put back in GA SE5 although Cubase opened ok, GA did not appear in the ‘New Track - Instruments’ drop down or in the VSTi tab. Any project I had with GA involved would not load GA either.
Everything used to work fine including GA and for no reason that I am aware of when I tried loading GA on an instrument track Cubase froze up. Then it wouldn’t even start without disabling all VST3s.
So when I use Steinberg Download Assistant to reinstall Groove Agent SE 5 (v. 5.2.10), the instal fails with ‘Installation failed due to an Unknown Error’ dialog box.