Users experiencing Upload Failed errors after editing files from Sharepoint

We have a similar problem, but it is intermittent. Occasionally a user cannot save a document back to SharePoint after editing it in Office. SharePoint (or Windows?) forces the user to save an Excel, Word, or PowerPoint document under a different name, or in a different location.
      We end up with multiple copies in SharePoint with different names, or else the user saves it offline and sends it to me to enter their changes in the SharePoint version. Does anyone else have this problem, or can you suggest a fix? I am recommending users edit in the browser as much as possible, but occasionally they need the full power of the Office application.
      We have also noted that when editing a SharePoint Excel document in Excel, the "Save" icon does not have the Shared indicator--the circular arrow on the icon. Usually it saves just fine, but occasionally we get the error and cannot just "Save" but must "Save As."
      We don't use Riverbed. We are on SharePoint online using Office 2016 or Office 2010.