The document "XX" cannot be opened - 3.1.5 update Issue

Hiya. I saw that there was someone else on the forums that had this issue, but after trying to reinstall as they did, I’m still having the issue.

When I go to open a project, I get the message that it cannot be opened. What’s weird is that I have an older file that is opening fine. It’s only the newer file that I need to access that I started a few weeks ago that is not opening. Also, I’ve attempted to create brand new files since this issue began and they will also not open, regardless of template or where I save the file. I don’t know what’s so different about the older file compared to the new stuff that’s making it work properly.

I am running Scrivener 3.1.5 on macOS Catalina 10.15.1

I did the autoupdate option when it prompted me and then went to the website to download manually and install that way. Despite having had Scrivener for a while, I’m still very clumsy when it comes navigating around it. I’m not fully sure what I have turned on and so on. But I do know that it was working fine about a week or two ago and now it’s not. Any help would be appreciated.