How to make IGMP Snooping work?

Question

HP

Windows server 2012 R2 gateway with RRAS
2 HP 1920 switches in a row.
With IGMP Snooping disabled, unsubscribing occurs, but the stream is poured into all ports.
I enable IGMP Snooping on the switches (thus: i.imgur.com/vpl58zs.png) and TV set-top boxes stop unsubscribing to RRAS when switching channels, while working perfectly through the desktop application.
On the gateway, after switching channels by the set-top box, this picture is i.imgur.com/rGjJGXF.png
At the same time, if you turn off "Drop Unknown Multicast Data" on the switches, at this moment even with IGMP Snooping enabled, the stream flows to all ports.
If you wait - it becomes so. i.imgur.com/jiNyprV.png
Add:
I double-checked, turned off Snooping, I switch channels with a prefix - it doesn’t unsubscribe (although I remember unsubscribing before, I don’t understand what’s the matter)
Add:
What are the pitfalls from the fact that I put small intervals?
i.imgur.com/xFPC7f3.png
What does the LF flag mean and what Query Interval (Sec) value should I set on the switches with these RRAS settings?