Roaming voice call problem

Using /e/ on a Moto G4 Play (harpia) in Germany it is roaming and making calls is possible but numbers called can’t hear me. Roaming Data also does not work.

In this case it is a Tesco sim from the UK roaming to o2 in Germany. Voice calls to the UK work, surprisingly.

It happened on /e/ versions 0.17q and 0.23q. What could be the problem?