Manuscript folders won't export?

Hey folks, this is my first time posting here so hopefully I’m in the right place.

I’m having an issue exporting my project. I tried to export the entire manuscript to rtf as a backup, but only about half of the folders successfully exported–the others ones gave me the message “Error: Could not open file for write.”

I can open and edit all of these files in my Scrivener project without difficulty. Nothing seems wrong with them until I go to export. I’ve tried exporting them individually as well, and get the same message. Does anyone know why this is happening, and how to fix it?

Possibly relevant: I’ve gotten some strange messages from my OneDrive (which is where I set Scrivener to automatically back up to) about how once files are deleted they can’t be retrieved, and some of the files they’re listing are from Scrivener. I haven’t manually deleted any Scrivener files from OneDrive, so the message was very puzzling. But once again, it doesn’t appear that any data is actually missing, despite these messages about files being deleted. What the heck is happening?!