Many months ago, there was a thread I started about crashing when saving with either of these instruments loaded.
I know this was only happening with some of us but it was a deal breaker for those that it was happening to. Cubase would freeze when saving when either of these two instruments were loaded on a instrument track when saving.
Anyway, tonight I figured out something that you could do and avoid this bug. It worked for me at least.
Go into Devices/Plug-In Information and make sure that for both Trilian and Omnisphere both have ASIO guard checked. Mine defaulted without being checked and once I checked them I didn’t get this save crash/lockup that I was getting.
If this info even helps one person, I am glad I posted because this was a terrible bug.