Your AP has its DHCP server shut down, router-mode is shut down, etc ?
Yes, it is in AP mode. It offers quite a few modes.
AP Mode
AP router
Client Router
WDS Bridge
WDS Router
and I think a few others, at any rate its in AP mode.
Also, the Mac addresses are shown in PFsense DHCP lease lists, however when the captive portal is on with the Mac pass through, it lets every device passthrough with the first logged in user.
Any AP does.
If that one is not it is either in a router mode, not an AP mode, or is for some reason proxying ARP or something of that nature.
In either case you are probably going to get a faster reply asking on a forum specific to that product.
I didn't know those existed lol, will do.