Thanks for the update, @John_Tracy. 
I'm starting to think your issue may actually be related to the thread that you previously linked (and recently bumped). Looking back at the internal conversation from back then, we also weren't able to reproduce that reported behavior. My attempted reproduction, which I've shared below, works as expected without any manual tweaks.
This makes it particularly difficult to diagnose, especially in a self hosted environment. Hopefully we can shed some light on it if you join Office Hours.