I wonder if what you’re seeing is the same thing as I reported in the following thread:
If it is, in my case, if I kill Cubase with Task Manager, then start it again, it starts just fine and doesn’t hang. I do have the latest iLok Manager since this is a new PC build. The hang on VST3 scanning has only occurred twice thus far, once on my first Cubase startup (on Monday) and once on Wednesday.
Most of my iLok authorizations (and, I think, all my non-iLok authorizations) are activated to the local system. However, UAD Spark plugins have to use iLok Cloud, so my thinking at this point is maybe there was some temporary biip with iLok on my system being able to connect to the iLok Cloud server on the two times when it hung. Of course, that is if the hang actually did relate to iLok.