Now I have re-installed Cubase 9.5, Halion 6, and VST Ultimate1+ and necessary updates. I launched C9.5 and everything works and there is no more missing content. I just had to be sure to tick “install for all users” every single time.
Now. Time to install Cubase 10 and see how it goes…
Everything went well. It seems what caused the problem was that at some point I have installed content without the “install for all users”. That is why content has been in 2 separate locations and that is why my cubase has been all over the place.
So I removed the Steinberg folder from both roaming/steinberg and at Programdata/Steinberg and re-installed everything. It was a hassle but now everything works.
But for some reason my halion sonic is blacklisted…it was the 64-bit version