I've never encountered this before upgrading to Office 2016, so it may be related. A coworker edited a paragraph in a Word document that is on a Sharepoint server, but then saved the change and closed the document (even restarted his computer). However, the paragraph still shows as locked:
To avoid conflicts, you cannot edit in this area until USER finishes editing it and uploads to the server.
Both of us have cleared the Office file cache as described towards the end of this article, but it did not unlock that paragraph. Also, it does not show that user as one of the users editing the document. This paragraph is also locked to users opening the document in Word 2013.
So my thoughts are that this must require some work on the SharePoint server itself (the paragraph lock information must be held there somewhere)...anyone know what that work would be?