Session Expired - Please refresh error message

Another user and I are working on the same word document online. When he works in a table entering data, we both receive the "Sorry your session expired. Please refresh the page to continue". This only happens when he is entering data in the table. He can copy and paste tables in the document and he can enter text in other places without issue. It is only when working inside the table. I receive the same error when he does even if I'm not doing anything in the document. I could just be watching what he is typing and I get the error. Any suggestions?