@gulickx The issue at the moment is the dialog window to set the carrier selection to manual/automatic it has been removed by the devs.
It hasn’t happened to me with Kompakt yet, but with my 2nd sim in other phones in some countries I have the same issue where it should connect to a specific carrier otherwise it won’t work.
Since the dialog window it’s not there you can’t select the dialog manually if the auto mode doesn’t work properly. And from experience the auto mode doesn’t work properly in a lot of countries.
As you can read in this topic Urszula said that it will come on the next update. Theoretically should resolve this issue.