Transparent proxy and netflow

[adk20]

Dear community,

I am running a transparent HTTP proxy on my OPNsense box. It appears that some of the traffic from LAN to the Internet is not represented in the netflow diagrams. So far I didn't have the time yet for a thorough investigation but it appears to me that HTTPS traffic is counted by netflow whereas plain HTTP is not. Could the port redirection rule for the transparent HTTP proxy be the cause for this?

Under Reporting > Health > Traffic, all traffic is counted and the digrams are correct.

Any ideas are much valued.