I'm having a go at shortwave since it got added in the repo.
As I was quizzing myself to see if I can differentiate a 320aac stream to a flac one, I noticed that if you use the mute button on Raven for shortwave the sound slider goes to zero (also in app), whereas it does'nt for other apps.
Here's a quick vid snippet to my lacky explanation, although it won't last.
Not sure if this is a Solus integration, BuddiesofBudgie or shortwave issue for ticket opening.