Until I can get this figured out…going to use a whitelist table. It works reliably. Only issue is that it doubles the amount of user rows 
What I’m currently doing in one of my tables is replacing the email with a version that has the word ‘Archive’ attached to the front of the email. This email column is a row owner column, and the goal is to effectively break Row Owners. Then I have a backend script that will eventually move that row to an unused table and remove it from the original table. So, I can confidently say that Row Owners shouldn’t be a factor when changing and email address.
I’m guessing in your case it’s the fact that email is part of the user profile configuration, and like roles, it automatically reverts. When I played around with this stuff back in the day, I think I was manually changing the email in the table and that’s when I got booted. I don’t believe I’ve ever tried replacing an email used in the user profile configuration via the app.
I guess you could maybe have a separate admin app where the user table is not the user profile. Then it would work and function like a regular table and you should be able to charge the email.
I’ll try to poke around today and see if I can figure something out. Maybe it’s just that Glide doesn’t allow either Roles or Emails to be changed via the app since they are both crucial from a security standpoint. Maybe it’s some kind of underlying protection from people who might be able to hack there way to bypass the front end interface to change underlying values. 
Interesting. This is probably the issue.