Cubase 9.5 stalls/blacklists/crashed when scanning VSTs

Hi, I’m running the current version of Win 10 64bit, and Cubase 9.5 Pro.

This started with installing an update of Slate’s VMR on Sunday. Load times were excruciating (20+min), and VMR got blacklisted.
I uninstalled VMR and reinstalled it, and things seemed to be okay on Monday (I worked on a small mastering project, using almost exclusively a handful of Slate plugins).
On Tuesday, I installed the new bundle from iZotope and SoundToys 5. I have versions of software from both of these vendors already.
Well, something broke it all.
Since I’ve uninstalled/reinstalled everything, twice. Including a clean install of Windows.
I’ve tried having nothing on this clean Install, but Windows, necessary graphics drivers (I use two Raven MTi2s), Cubase, and the eLicenser and iLok software.
Install for Cubase was excruciatingly long. Hitched on the Halion stuff, particularly. On loading, long scan times for VSTs again (only Cubase installed), and it started blacklisting its own plug-ins (Halion, Padshop, etc).

I had a chat with someone from support, who ultimately sloughed it off on 3rd party vendors, and unceremoniously closed the chat when I asked about following up.
I’ve been in constant contact with Slate Support via email since Tuesday afternoon.
I’ve spent 4-6 hours a day installing/uninstalling/reinstalling things since.
I had to send a client home Tuesday evening because I couldn’t get a project to even LOAD. I’m out of business.
I’ve been extremely patient, and tried everything I know, as well as everything both Slate and the Steinberg chat person suggested.
I’m at my wit’s end.

Please help, somebody.