@evenmoreconfused You're overthinking things.
Sorry, I should have been more clear. I'm not blocked or anxious that this gets resolved quickly -- I've been getting to Rev Que using other browsers for weeks now -- and I'm only chasing this down out of community spirit and curiosity. In other threads here, developers seem anxious to identify compatibility issues vs other browsers.
Just go through the troubleshooting steps linked, including testing in a clean profile and disabling extensions, clearing cache+cookies etc.
Yes, that's clear to me, but if I do that I will reset / lose whatever it is that's mis-set. I want to carefully locate whatever the cause is and try to understand how it became wrong (I was a software developer for 40 years before retiring half a decade ago).
When I follow your steps in the first post, I get this page:
Yes, that is the correct next page in the five or six page login sequence to our wonderful tax collector here. It seems to be just this one browser instance in one profile that screws up.
Thanks for all your help,
Paul