Omnipresence error with a particular file


I have a problem that as soon as I move a specific file into my OmniPresence folder on the Mac I get the error shown below.

Unable to create URL to temporary items directory for 

I would welcome any thoughts on what might be causing this. I’ve renamed the file, saved it as a new version but still have the same problem. This file has synced quite happily before.

Both OmniPresence and OmniOutliner are the current release versions.