Hi,
I have fully migrated my router to the new bridge implementation introduced in 6.41.
Everything works fine, just IGMP Snooping doesn't work.
I have one bridge with multiple VLANs. I get IPTV from my ISP on VLAN 3999 and tag it in I also tag ports that go to the STBs, the same way ()
IPTV works. If I then enable IGMP snooping, it works fine But in my bridge there is also a PPPoE server on VLAN and IGMP snooping brakes that.

Is there a way to enable IGMP snooping only on one VLAN? I already tried to disable unknown-multicast-flood instead of IGMP snooping on IPTV ports, but it does not work.

Which RouterOS version are you using? There was a bug in 6.41 related to IGMP Snooping in 6.41, the problem description seems to match your problem, but it was fixed in 6.42

If you are already using 6.42, then you should send a supout.rif file to support@mikrotik.com since this might be a bug.

I have the latest RouterOS (6.42.5).

What was the outcome of this?

I worked on an IPTV network recently using CCRs in bridge mode with IGMP Snooping and PIM Sparse and I don't think we ran into any issues. Maybe it was a problem in the older ROS version?