I have been having the same problem. I tried to load some saved mgu songs when in VST mixer. These songs will open in BIAB and are stored on drive. However, they will not load into the VST when activated in Studio One I am running BIAB 2021 and Studio One 4 off of a portable hard drive. I'm planning to upgrade studio one to ver 5 shortly then I will move everything to my C: drive.

I'll keep playing with it to see if anything changes. I need to double check vst version

jim