HomePod stop working after tvOS 26.1

I have a problem with the HomePods, configured in stereo via AppleTv, after updating to TvOs 26.1 (the HomePods are also updated to 26.1).

They are not recognized by AppleTv as an output source, while from the Mac, I can stream to only one of them. I've already tried to restart everything (HomePod & appletv), without success. I also tried to "separate" and re-pair them, without success.

Can anyone help me? Thank you