This is not so much of an issue report as a simple solution to many problems.
After days of frustration and experimentation I have found out that plugging the eLicencer on a USB2 port was the solution to such problems as: projects crashing Cubase on open, projects freezing while loading specific plugins/channels, Cubase 8.5 freezing on exit, Cubase 8.5 not opening at all, crash/freeze when (re)scanning plugin directories, general instability.
Now, this might be an combo-issue related to Windows 10 and/or specific motherboards (can’t cross-test), but the benefits are so great that I simply need to document it here for other people who have been (or still are) in the state of despair I was after upgrading to C8.5. Basically went from being unable to use Cubase at all to a very stable system with just a simple move.
So there, move your eLicencer from USB3 to a USB2 port. Hope this helps. Cheers.
P.S. Steinberg, if you could verify that this is an issue and (perhaps) update the eLicencer drivers it would be great.