I couldn't fix it, and also wasted a lot of time on it. In the end, I decided to run everything that works out of the box from the secondary, and those that give problems I move them to the primary drive. That way everything works. Ideally i'd have just all of them in one drive, but it's just not worth the effort to find out and fix each of them, it's some kind of nightmare. In the end, it's just a game location.
For those interested, from 13 games installed, 4 did not work in the secondary drive and 9 do. So it's not too bad of a %.
I like the post, and have experienced similarly after moving to GOS. What I also like is I could put some apps that I still need (but dont really like) just in case in a Private Space (eg Whatsapp, or banking), this way is always closed and just check it once a day, with a specific purpose. No notifications from there whatsover. Most people (the important ones anyway) know they can reach out immediately if needed via Signal.