Hello
First, many big thanks to team and contributors who build and maintain pfSense.
It happens that pfflowd is still broken after upgrading pfSense to 2.2.1.
Same package version for pfflowd : 0.8 pkg v1.0.2, including after re-install.
I checked and no flow packet is received at collector side. It did work fine up to 2.1.5.
Surprisingly, pfflowd doesn't crash immediately, but 5 or 6 minutes after (re)starting the service.
From Status\System Log :
Mar 20 23:30:02 - pfflowd[29286]: pfflowd listening on pfsync0
Mar 20 23:30:02 - kernel: pfsync0: promiscuous mode disabled
Mar 20 23:30:02 - kernel: pfsync0: promiscuous mode enabled
Mar 20 23:36:49 - pfflowd[29286]: Unsupported pfsync version 5, exiting
Hope this will be resolved soon, for now I will stick to 2.1 to continue to have a look at traffic from netflow collector.