sFlow format is much different from NetFlow, that why Wireshark has separate parser for sFlow, to see the content of the packet right click it, select Decode as.. > last tab > select SFLOW from the list on the right.
Now for NTA: NTA is able to process sFlow if it contains information required by NTA, typically TCP/IP packets:
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Only known issue from top of my head is with TRILL protocol causing sFlow stream to be rejected by NTA.
