I suspect this issue is what's causing me some issues with my metadata.
On my PC, about a week ago, I suddenly stopped being able to see tags or authors in file metadata get suggested when I typed part of the word. For example, in the past I'd type "Com" into the tags field and after a few seconds it'd suggest "Complete". Same with Authors.
Since a week ago, the dropdown of suggestions has never once appeared, and it takes me two hits of enter to confirm an Author addition, where it used to take one.
My Laptop didn't have this issue until halfway through today. Everything was working as it should, until my laptop started getting a little sluggish so I rebooted. Since that reboot, the metadata editing has been broken in exactly the same manner as on my PC.
I went to event view to see if I could find anything that might suggest what happened, and today, 18 September, I have... 48 of these errors. 349 since the start of September, including before I ran my update. Nothing before September.
that sounds more like a bug in office than this problem. I believe the issue we are discussing here is device metadata not document meta data. I recall seeing this as an issue in a discussion not so long ago, I suggest you try and see if there are any updates pending for office (File > Office Account > Updates) failing which do a full repair of Office and see if that fixes it.