Does File History change folder permissions while running?

I'm having a seemingly random permissions issue, but I have a theory...

I suddenly can't save to my Documents folder. I get "You don't have permission to save in this location. Would you like to save in the Documents folder instead?" I get this no matter whether I'm trying to save in the Documents folder or any sub-folder.

This is brand-new today, and I haven't permitted any updates since last night, when I was able to save in Documents without a problem.

I was able to edit the permissions and regain access to the first sub-folder I encountered this on, but I also received an error message (which I dismissed and don't remember). But the permissions did successfully change.

The one thing that's different is that I'm running File History for the first time and it's still copying my files.

So, is it possible that File History is temporarily locking down folders so the data doesn't change while it's copying it? My web-searching didn't produce any helpful answers.

I'll see if I have permission again once the File History operation is complete, but it looks like it has a long way to go so I thought I'd ask. I'm hoping it is a temporary File History thing, I'm not looking forward to troubleshooting a permissions issue today.