No audio on Skype when using another application

I'm having an issue with my audio on Skype. If I do a video call without having used another application before the audio works fine. However when I'm watching a video on youtube, or stream web-radio or use messenger for calls first and then try to do a video call on Skype there's no audio at all (skype is muted, system audio still works fine)! It seems like only one application can process the sound card at a single time. How to fix this issue?

I'm having a fresh installation of 18.04 and before I switch when I was on 16.04 I had no issues at all, I could use Skype and everything else (youtube videos, seb-radio) at the same time.