Are you aware that Google Cast does not work sometimes? Especially after an SA30 firmware upgrade? You have to use Google Home and setup your SA30, next SA30 will be ‘visible’ through Google Cast. I’ll try and see if I can find the relevant support ticket for you.
Amazon Music HD kept dropping out every time after a track or so. After trying out various things over a few weeks, like updating the SA30 software, I simply switched to Qobuz and it streams perfectly. So that’s my solution.
assuming you are chrome casting or Airplay since Amazon music is still not airable as far as I can see. Would be interested to hear how you got Qobuz perfectly working as I’m having no end of trouble at the moment!