[Darryl Ramm]

If trashing prefs and stuff comes back that really tells you something is corrupting preferences... or some valid prefs entry is messing up other stuff, and after checking again everything is supposed to be compatible it's time to contact Izotope support. Even if it turns out to be an underlying problem in Pro Tools start with Izotope support, you'll likely make more headway there, at least in them mitigating a problem.

I would test to see if you can reproduce this on other sessions, when starting from a clean empty session... sometimes a corrupt session cause other things to wig out.

If you wanted to be super nice to Izotope support, see if you can track this down to trashing one particular prefs file and give them a before a copy of that file that causes problems.