(hopefully final) Update:
The good news for Cubase users, there is a solution.
What I did:
Installed Scaler with only the standard sounds.
Result: Crashed Cubase when attempting to open GUI.
Rebooted computer.
With this installed version I turned off OpenGL.
Result: Crashed Cubase when attempting to open GUI.
Rebooted computer.
Uninstalled Scaler
Rebooted computer.
Reinstalled Scaler with extra sounds installed to a separate internal SSD
Result: Crashed Cubase when attempting to open GUI.
Rebooted computer.
Turned off OpenGL
Rebooted computer.
Result: Crashed Cubase when attempting to open GUI.
Rebooted computer
Uninstalled Scaler
Rebooted computer
Reinstalled Scaler with extra sounds installed in the default location
Rebooted computer.
Result: Cubase DID NOT crash when attempting to open GUI! Yes! It friggin’ worked!!!
Bottom Line:
If you install everything, including the extra sounds, to their default locations, Scaler 2.8 works with Cubase.
Changing anything in the default installation settings before doing the install and Scaler crashes Cubase every time you attempt to open the GUI. (you CAN choose not to install the AAX version and still live to see another day)
This bug is blatant. Scaler folks need to test their products more thoroughly before release.