Cannot click into or scroll word document after opening .... Until I hit Ctrl+Home or interact with some options in the Ribbon Bar

Question

Some of our clients have started reporting a strange issue in Microsoft Word after we open documents using Microsoft.Office.Interop.Word automation

When they open a Word document they think that MS Word is hanging. The first indicator that it's not exactly that is that they can still interact with Microsoft Word. The Ribbon Bar is still accessible.

The Vertical Scroll Bar, too, is accessible. They can drag it up and down and the scroll bar itself moves. But the document doesn't.

When clicking into the document with the mouse, the cursor doesn't appear where the user clicks.

At that point I just hit Crtl+Home and ... whadyaknow ... suddenly the cursor appears at the start of the document and from that moment on the document is perfectly fine, fully accessible.

I found that, similarly, the following actions appear to restore full access to the document:

Going to the View tab in the Ribbon Bar and toggling the Show Gridlines option.

Going to the View tab in the Ribbon Bar and switching the Page Movement option from Vertical to Side to Side and back again (or vice versa)

Going to the Review tab and toggle the "Show Comments" button off.

So can anyone shed light on what might be going on here and how it might be avoided? My guess is that there is something in that Word Document that happens to get the cursor "focus" when the document is opened, but that is not immediately visible to the user. Hitting Ctrl + Home brings focus back to a point where the user can see the blinking cursor and after that the document behaves normally. Once the user does any of the above, including Ctrl+Home, the problem "goes away", clicking into different parts brings the cursor to those points as it should, and the vertical scroll bar now causes the document to scroll up and down as it should.

I'm not sure whether this has anything to do with anything but I managed to see this behaviour in a 64-bit version of Microsoft Word, build 16.0.28025.20160

Firstly: we open documents using Microsoft.Office.Interop.Word automation. So we create a Word.Application, open the Document, activate it, that sort of thing, all programmatically

Secondly: The documents that cause this problem have Footnotes in them. I tried converting Footnotes to EndNotes but that doesn't help. Removing them altogether, on the other hand, seems to make all the difference.

So I reckon that this problem has something to do with the presence of Foot- or Endnotes in the document.