So you sniffed on the machine your sending too?
which is actually the gateway for these servers
Does it see the traffic and answer it? If it doesn't answer it but sends to wrong gateway?
It NOT going to work if the gateway for the machines traffic being sent to is not the pfsense forwarding on the traffic..
If you want actual support then
https://www.netgate.com/support/contact-support.html
Here is what I can tell you in the 10+ years I have been on this site and using pfsense port forwarding issues are always PEBKAC...
BTW your haproxy is prob working because it does a source nat.. So traffic would be coming from pfsense IP, ie the whole proxy thing ;)