I have the same issue, but not only with Gravity, but as well with the other libraries i purchased (Granular symphonies).
the same issue happen with Retrologue 2, i only see the factory library content, and to see the user library (soul and vst classic from Dave Polich) i have to use the tree view. it’s pretty annoying. i will try the workaround found here, hoping it will fix it, if it will thanks in advance, i’m a bit afraid to loose all my parameters in Cubase… don’t know how to do a backup from them, as i spend hours and hours to test sound and rating them, and all other stuff. i’ll come back here to tell if it’s fixed the issue on my side ! Thanks !
Edit : the solutions above worked, last issue : cubase don’t see in the content set list, my last purchase : granular guitars. don’t know what to do…