[Saving issues with latest Beta update]

I'm not sure what's going on here but I just updated my publisher Beta (as the program suggested). Now all the sudden I can't save a particular document. Every time I try to make a change to the file and save I get an error message. (I'll attach it so someone can see what it is.) It seems to maybe be only related to this file? I've opened a few other Affinity publisher files, created a change, and saved without an issue. I've also created a few new files and saved without a problem. I'm not sure if its beta related or somehow my file became corrupt either way could use a little help!