This is probably duplicated elsewhere, but this at least bumps this up a bit. Mileage may vary, but it was the solution that got things running.
My router is:
Add-on dual port NIC
Pfsense 2.2.4 (as of this post)
Port 1 - IPV4 LAN
Port 2 - IPV6 LAN
Port 1 - IPV4 WAN
Port 2 - IPV6 WAN
IPV4 /29 static block
I am going to assume this will work correctly for a single WAN and a single LAN port sharing IPV4/IPV6
Interfaces -> WAN -> IPV6 Config Type -> DHCP6
Interfaces -> WAN -> DHCPv6 Prefix Delegation size -> 60 (this is what made it work for me)
Interfaces -> LAN -> IPV6 Config Type - Track Interface
Interfaces -> LAN -> IPV6 Prefix ID - 0
I had been fighting this for months with no success, came across a posting on the PFSsense boards ( https://forum.pfsense.org/index.php?topic=98044.msg546082#msg546082) and as soon as I set the /60, all of my connections began working. Hope it helps.