For your information.
The IGMP traffic coming from IGMPPROXY goint to the multicast range of IP used by my provider for multicast IPTV is filtered out by BLACKLIST BOGON
Apr 9 10:40:54 ipfire kernel: BLKLST_BOGON IN= OUT=red0 SRC=[censored] DST=224.0.0.251 LEN=32 TOS=0x00 PREC=0xC0 TTL=1 ID=0 DF PROTO=2
Apr 9 10:40:56 ipfire kernel: BLKLST_BOGON IN= OUT=red0 SRC=[censored] DST=224.0.0.251 LEN=32 TOS=0x00 PREC=0xC0 TTL=1 ID=0 DF PROTO=2
Apr 9 10:41:12 ipfire kernel: BLKLST_BOGON IN= OUT=red0 SRC=[censored] DST=224.0.0.2 LEN=32 TOS=0x00 PREC=0xC0 TTL=1 ID=0 DF PROTO=2
Apr 10 08:10:18 ipfire kernel: BLKLST_BOGON IN= OUT=red0 SRC=[censored] DST=224.0.0.251 LEN=32 TOS=0x00 PREC=0xC0 TTL=1 ID=0 DF PROTO=2
as you can see the forwarded packets going from my IP to a multicast IP address block (224.0.0.0 to 239.255.255.255, in CIDR notation 224.0.0.0/4 is multicast) with protocol 2 (can be ICMP and IGMP; in this case clearly IGMP as it happens in real time when I try to open a TV channel) get blocked by the blocklist, making impossible to receive the audio/video stream. I do not care about any TV stream, I noticed this because I was testing the next version of IPFire. I thought to leave a message in case someone comes looking to troubleshoot a failed IPTV stream.
EDIT: I forgot to say, if I remove the filter, the IPTV stream works perfectly fine.