Application being identified as "non-syn-tcp" and is allowed/blocked

Application identified as "non-syn-tcp".
The traffic is being Allowed or Dropped depending on the tcp-reject-non-syn settings.

• PAN OS
• Network with Asymmetric Routing

• When the firewall receives a non-SYN first packet, it would be allowed or dropped based on tcp-reject-non-syn config and the application is identified as non-syn-tcp app. 
• This could happen when there is Asymmetric Routing in the Network environments. 
• Asymmetric routing is a situation where packets follow a different route in an outbound direction than they follow when returning in the inbound direction.

•  If the traffic is being identified as non-syn-tcp and is dropped/allowed, and needs to be allowed/blocked, you may need to configure non-syn-tcp globally or per zone basis. See below article for reference:

•  Network architecture can be changed to eliminate asymmetric routing.