N3000 (6.1.1.7) igmp snooping issue

G'day!

I'm setting up a new N3048P switch and having a weird issue with multicast packets being flooded to all ports in the Vlan ONLY when there is nobody joined to that multicast group, ie. 'show ip igmp snooping group' shows that the table is empty 'There are currently no entries in the table.'

If there is one or more hosts that joined the multicast group the IGMP Snooping works as expected - no flooding - multicast packets arrive only on interfaces where hosts have 'asked' for it and are in the IGMP Snooping table as per 'show ip igmp snooping group' command output.

Has anyone seen this before? Is this a normal behaviour?