I have a couple of Docuware systems that seem to have the same issue.
One has issues editing PDFs (PDF checklist form), tells them the document is locked by that same user. They will wait at least an hour to try again and sometimes they wait until the next day. This happens to everyone that tries to edit the PDF checklists.
The other system has issues storing and appling stamps, they get the same error about the document being locked by that user. They will close out of all their application on the PC to get past this error. This doens't happen to everyone, but does happen to more than one person.
In both cases it doesn't happen everytime and they are on 6.11.