As with many protocols on Nexus, you must first enable the HSRP feature
NX-OS adds some functionality to HSRP when you’re using vPCs. In short, when a packet is received on a routed (nonswitch) port and is destined for the HSRP VIP configured on the router, the packet will terminate on that router, even if it is not the active HSRP router. Packets received on Layer-2 interfaces will be forwarded to the active router.
Why is this important? First, this will help to eliminate traffic on interrouter links. Second, if you’re not aware of this behavior, you may go quite mad trying to figure out where traffic is flowing when you think it works the traditional way. You have been warned.
vPCs between two Nexus switches will forward traffic through both the active and standby routers. Cisco documentation recommends that you configure the HSRP active router to be the same device as the primary vPC peer.