Excel/Word crashing when co authoring

Yes, we have a client that has been having this issue. Here is what I've been able to find:

• User A and User B open the file from SharePoint Online using "Edit in Browser" - No Problems.
• User A and User B open the file from SharePoint Online using "Edit in Word/Excel"  - No problems ( I think)
• User A opens online and User B Opens in local app - May have an issue.
• User A opens from OneDrive synced to SharePoint, User B opens from SharePoint - Will randomly crash.
• User A opens from SharePoint, either in browser or app, and User B opens from SharePoint in File Explorer, then opens in local app - Random crashes.

The underlying problem appears to be the Auto-Save feature added to OneDrive for Business in the fall coupled with having OneDrive sync to SharePoint enabled and allowed. All the documentation on coauthoring I have seen indicates that you need a shared source for the files, and on-prem SharePoint, O365 SharePoint, One Drive and OneDrive for Business are all candidates, but nothing says anything about if you have SharePoint synced with OneDrive. 

That said, I also opened a ticket with Microsoft, and was verbally told, definitely opening from two different locations, (i.e. SharePoint and OneDrive) definitely WILL break coauthoring and cause the applications to crash. But there is NOTHING in print as of this writing that officially states that.

I think this is a scenario that Microsoft didn't think of, and didn't test, and the Office Suite has no error handling for.

Our only solution at the moment is to disable OneDrive sync to SharePoint, but I have one client that doesn't accept that answer, and getting detailed information involving all the possible parameters from end users is nigh on impossible.