Many thanks. It does work and I did some tests like establish a FTP session and download some files but nothing is log during the session. When I close the ftp session, I get a log but the bytes send/receive does not match the transfer I did.
If your device has NP (Network processor) after the connection is setup the traffic gets offloaded to Network processor, due to which we will not be able to see the complete traffic details in the log.
We can disable this option on the specific firewall policy
config firewall policy
set auto-asic-offload disable
You can also refer this KB for more information regarding the same