We have a quickfields agent (10.3.0.81) that creates copies of documents including the metadata and security tags.  But sometimes... the security tag is not applied to the new document.  

As a workaround I created a workflow that would double check the copies and fix them.  It sends me a report when this happens.

What could be causing this?  It will run for weeks, processing hundreds of documents without a hitch then suddenly I'll get dozens of fails in a single day.