I really don't understand what's happening...
I now went to try to do the same Routine but using Spotify instead and it does the exact same thing... If I have the Open App: Spotify and then Play Music Spotify, it opens the app but doesn't play anything...
If I only have the "Play Music - Spotify" (without the Open app instruction first) it doesn't do anything...
So it's not just a Youtube Music issue... it just opens the app if I tell the routine to do it but it doesn't play any music if instructed to do so or not...