"Command + W" now doesn't work

File --> Close now doesn’t work
… nor Command + W (on MAC)

This, just, all of a sudden…

The only thing that works is clicking the red X in the top-left of the project window.

—closed down Cubase, reopened… same problem with completely new project

—UPDATE: WAIT… it gets better… also Undo and Redo now don’t work… nor do Command + Z, etc…

Follow-up:
This is related directly to Waves SoundGrid 12 / StudioRack, which just came out yesterday.
The problem goes away when rolling back to SoundGrid 11.
The problem does not happen in Logic. It’s Cubase specific, perhaps Cubase 11 only. And perhaps only to MAC OSX Mojave 10.14.6… and perhaps only specific to me. Ugh…
Waves has been notified.
I do hope I just saved you a full day of troubleshooting Cubase.