Settings/App Store apps crash after login attempt
In the App Store app on Apple TV, or in the Settings app in users and accounts, I can't log in with my store ID any longer.
I use 2 separate emails, my iCloud one for the Apple TV account and another one for the App Store.
It seems that my store ID was logged out (it's still listed in previously used emails) and that now whenever I want to log in again, the App Store app or the Settings app crashes (goes back to home screen).
The password is correct (wrong passwords don't crash the apps, they are refused). The right password leads to a crash.
Apple TV restarts don't help. I also can't invite myself via the Home app on iOS, it says invitation failed.
Curiously the Home app still lists the correct store ID for media under my user/name.
Hardware is Apple TV 4K, software is latest.
This means I can not currently download, buy or update any apps.
Thanks
Apple TV 4K, tvOS 13