Basic things might have beenchecked:
show feature >> check multicast enabled.
Is your PIM enabled on the interfaces ?
Who is your RP ? If you are using PIM spare mode? Are the interfaces configured with ip pim sparse-mode?
if it is layer 2 is your igmp snooping enabled or disbaled?
Please find muliticast configuration guide for this product:-http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/6-x/multicast/configuration/guide/b_Cisco_Nexus_9000_Series_NX-OS_Multicast_Routing_Configuration_Guide/b_Cisco_Nexus_9000_Series_NX-OS_Multicast_Routing_Configuration_Guide_chapter_011.html
HTH
Regards
Inayath
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