I upgraded to the 8.5, as well as installed the latest maintenance update (8.0.35) and noticed that Media bay crashes while searching through loops/sounds. I tried the Loop Browser and got the same response.
It gets hung up on the spinning blue wheel and the only way to unstick this is by restarting the CPU (as using Task Manager shows Cubase “not responding” which will allow me to force quit Cubase, but this only lags the entire computer and still shows Cubase lingering in the Process Tab not allowing any further “end task” to be done, FORCING a complete restart).
I took the liberty of going into the folders -----App Data/Steinberg and rebuild the Media Bay library, but I still get the same result. I also trying reinstalling the upgrade and update, but no luck.
Everything else seems to be fine up until I launch Media Bay or anything else that runs the Loops and sounds, which initiates the spinning blue wheel o’ death… Any help to get this out of the way is MUCH appreciated, as I just took on some work and faced this while starting the project 
My system info is below… Thank you in advance!
--------------System INFO----------------------
Cubase 8.5 (update 8.0.35)
HP Intel Core i5-4430CPU @ 3.00GhHz
Ram- 16gb
Windows- 8.1 64 bit OS
I/O- Steinberg UR28M