Studio 2019 SR2 verification hangs, never completes, (MS Grammar Checker disabled)

Hi, verification has completely stopped working in Studio 2019 recently, and is now stopping me from delivering my current job :(.It hangs forever at around 40%, and cancelling also hangs, requiring me to end the task in Task Manager.

The only file I have managed to verify lately has been a 57 word file. (The other file in the current project which I urgently need to verify is 12,465).

I have disabled MS Grammar Checker as I understand from one of Paul Filkin's posts that it can be a culprit.

I have also disabled numerous other add-ins "just in case".  To no avail. 

Any suggestions very gratefully received (I have a powerful 1 year old PC and of course I have endlessly restarted Studio, my PC, upgraded Studio etc...)

Very grateful for any insights.