Hi @Timonko
Welcome back to the Sonos Community! And, apologies for the delay.
Sorry to hear of the issue you are having with your surround speakers. To be sure I understand you correctly, I’m going to reword things a little: when playing music to Arc via the Sonos app, you hear music from the Arc, the Sub Mini, and the surrounds, but when you play TV audio, only the Arc plays - is that correct?
If so, the first thing to do is to check the Now Playing screen for the Arc while TV audio is being played. If it reports PCM Stereo or Dolby Digitial 2.0, then it is expected that you hear no audio from the surrounds (note that Sub Mini should always be playing with Arc). For you to hear surround sound, the playing media must be recorded in that format.
If the Now Playing screen reports 5.1 audio or Atmos, however, and you still hear nothing from the surrounds, please first ensure that what you are watching is likely to have surround audio - a crowd or action scene will, but a dialogue scene probably will not.
If you are now (or before - I’m just covering eventualities here, and don’t mean to imply that you didn’t already understand everything I wrote above) convinced that the speakers are not playing while they should, I recommend that you try rebooting the Arc - please unplug it from power for a few moments, then plug back in and wait for it to finish rebooting.
If that has not helped, I recommend you remove the surrounds and Sub Mini from the Arc, then add them back again. When removing the surrounds, you’ll be asked where to put the One SLs - just put them in temporary rooms (don’t stereo pair them). It may help to add the Sub Mini after the surrounds.
Settings icon » nroom with Arc] » Remove Surrounds
Settings icon » sroom with Arc] » Remove Sub Mini
Settings icon » proom with Arc] » Set up Surrounds
Settings icon » proom with Arc] » Connect Sub
Finally, I recommend you get in touch with our technical support team who have tools at their disposal that will allow them to give you advice specific to your Sonos system and what it reports, if nothing above works.
I hope this helps.