I have had the same problem as the OP in the last two days. I can hear voice Atis but not ATC, I am not able to transmit either. I flew a Vatsim flight two days ago and everything was normal, I did nothing to the settings but when I wanted to fly from EGGD to EGHH yesterday morning I found myself with this problem. Later I couldn’t hear voice atis either, but now this morning I can.
It’s quite a weird one imo. What is different between voice atis & atc? 
I think this VR venture is sent to teach me patience - and I think it’s working! 