this answer is not correct. please check the guide https://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/5_x/nx-os/system_management/configuration/guide/sm_nx_os_cg/sm_15netflow.html#wp1088665
Guidelines and Limitations
NetFlow has the following configuration guidelines and limitations:

You must configure a source interface. If you do not configure a source interface, the exporter will remain in a disabled state.
You must configure a valid record name for every flow monitor.
A rollback will fail if you try to modify a record that is programmed in the hardware during a rollback.
Only Layer 2 NetFlow is applied on Layer 2 interfaces, and only Layer 3 NetFlow is applied on Layer 3 interfaces.
If you add a member to a port channel that is already configured for Layer 2 NetFlow, its NetFlow configuration is removed and the Layer 2 configuration of the port channel is added to it.
If you change a Layer 2 interface to a Layer 3 interface, the software removes the Layer 2 NetFlow configuration from the interface.
Use v9 export to see the full 32-bit SNMP ifIndex values at the NetFlow connector.
The maximum number of supported NetFlow entries is 512K.
The Cisco Nexus 2000 Series Fabric Extender supports bridged NetFlow.
Beginning with Cisco NX-OS Release 5.2, NetFlow is supported on switch virtual interfaces (SVIs) for F1 Series ports. Bridged NetFlow on F1 Series ports is not supported.