I recently got a new iPhone 11 Pro and cannot login to Premiere Rush and a few other apps. I get a message saying "An unknown error has occurred..." and then a long alphanumeric (looks like hex) string.
I had the same issue with Lightroom mobile but was able to solve it by signing in to the Creative Cloud app and launching Lightroom from there. That doesn't appear to work with Premiere Rush.
I called support and they had me resinstall the app with a phone reboot, which did not solve the issue. They also told me to wait for the app to be updated, which I think is unacceptable.
Has anyone seen this issue? Here's a screenshot of the error, the error code changes after each sign in attempt.