I have found a solution for people with two SIM cards:
You have to turn off App Support, disable SIM 1, enable SIM 1, disable SIM 2, enable SIM 2, turn on App Support again.
If cellular data was already enabled, you might have to disable it as well, then enable again, then everything works.
A bit tedious but for the moment I am glad there is a reproducible, reliable way.
Edit: typo