Thank you for your post and movie.
Even after watching your movie, I am unable to replicate the issue with FileMaker Pro 16.0.2 under both macOS Sierra 10.12.5 and Windows 10. I would like to get a clone of your file so I can determine why this issue is occurring. I have sent you a private message with instructions where to send the file.
I had the same issue, however since upgrading to 188.8.131.52 I cannot replicate this any longer.
A similar issue was experienced in the past (Sierra or El Capitan as far as I remember). Cause off the issue was indeed macOS related.
However, I would recommend always first deactivate all PlugIns and try to replicate a issue again.
To narrow this down to a certain PlugIn doesn't mean that it is the PlugIn to blame. The PlugIn would only be the trigger for a inconsistency of any of the involved platforms, OS' and applications.
It appears that disabling and re-enabling the MBS plugin did the trick.
Seems that by deactivating/re-activating, kind of a reset takes place which solves this issue (temporarily?).
As stated before, a PlugIn can also be just the trigger of a inconsistent behaviour with the OS or anything else.
You will learn a lot about such coincidences when playing with OS beta-releases …
I am used to get blamed for bugs.
Not every bug is one of mine.
That's exactly what I meant.
Nobody blames you!
All we do is to gather informations to have other users prepared with tricks and work arounds when this happens to them.
I'm sorry for you, but some of my customers still blame me for the FM12 disaster.
Life isn't fair!