Hi riley1...,
Looking through your posts, it seems to me that the problem is at the Sonos end. I have two reasons currently for thinking this which are:
1. When you play tracks to Sonos, the B2 uploads the tracks to Sonos and then the B2 waits for something else to do. At this point, the Sonos is in full control of playing the music. The B2 does not stream to the Sonos. You can see this if you open up the Sonos app on your phone or mobile device, you will see all of your chosen tracks in a play queue on the Sonos. Also you can switch the B2 off and this music will continue to play until the Sonos has played the last track.
2. You have tested the B2 output through headphones and the fault does not happen, which suggests that the B2 is working correctly.
A further thought is that could there be a problem with mixing the Sonos move with the other speakers?
Also is all of the Sonos software up to date? That includes the Sonos app and each of the Sonos speakers.
I have a pair of Sonos One speakers and they work perfectly, so much so that I am thinking of purchasing another pair.
Regards,
Peter.