Crash upon saving

I’ve got a new model…couple of days of working.
Absolutely no problems so far. Saving fine. Save A Copy As…also fine.
Just now, I hit "Save a Copy As…CRASH.
I did a forced save about an hour ago. No prioblems.
I open the file…it’s two and a half hours old! And there’s no backup!
And the forced save didnt’ work either apparently!

I go for my backup and it’s not there!
Backup is set ON and path is set to C:\Users, myname\Documents…
Nothing there.
How can there be no backup when the option is checked and the time interval is set?

Under AppData\Local\Sketchup, etc…there’s a TMP file of my model, but it’s a “nothing flle”…Zero MB.

So I lost two and a half hours of tedious work.
there’s not backup being made.
What’s my next step?

I’m on Windows 10 Pro and Sketchup pro 2019.