SharePoint - Invalid Argument Error on pdf upload to attachment field
I have a set up with Access 2013 FE pointing to SharePoint list BE in O365.
One of the fields is an attachment field which the client attaches pdf documents to. Occasionally, and seemingly at random, one user or another will get an error 'Invalid Argument' with options of OK or HELP when they try to attach the file.
It isn't always the same user or PC. It seems to just resolve itself after a day or two. I'm at a bit of a loss as to know where to start. Has anyone come across this before or have any ideas where to poke around??