I think that NTA 4.2.1 will track IPv6 as a protocol for summary of protocols, but does not yet save anything else from actual flows of IPv6 conversations.
For example, I cannot setup IPv6 Address Groups. I can't enter IPv6 addresses in any format in the Flow Navigator.
So I think adding IPv6 to the protocol list (see Settings> All Settings> NTA Settings> Monitored Protocols) is a first step towards IPv6.
I sure hope SW moves forward on IPv6 faster. It has been mandated for federal internet facing servers since 2012, and internally since 2014. Everyone is having trouble with it because so many vendors claim IPv6 compatibility if any part of their product can do IPv6 - not if all parts do. They key thing is that we need to monitor IPv6 to troubleshoot IPv6.