Can't backup projects since upgrading to CB 7.5.20

I’m bumping this from issues since traffic is much higher here - and somebody else MUST have the same problem…!
Problem is that I can’t backup a project if “minimize files” or “freeze edits” are selected.
I just get a message that “there is not enough space on the selected drive”. But there are lots of space free on the two different drives I tried.
If I deselect minimize files and freeze edits (BOTH have to be deselected…) I can back up.
But selecting one of these two options makes it impossible to back up.
The projects also generate a very large csh file.
It’s local drives and I have all permissions - I’m the only user and administrator.
This has happened on two different projects and it has NEVER happened before upgrading to CB 7.5.20.
It’s audio projects only - no midi or scores. They are app 2 hours long each.
Help please!