Thanks weaver.
DHCPv6 LAN side, not from isp.
I have now solved it, the issue was after I bound the LAN network on pfsense to the private VLAN (from native network device), it lost its ipv6, and I had to reinitialise the WAN for it to come back, once that was in place DHCPv6 was fine again, since my LAN DHCPv6 auto generates the first octets from the WAN assigned prefix, it cannot work without that in place, so thats why it was failing.
Also to help other newbies I will post a guide at some point, on setting up isolated subnets for things like guest wifi. The guide will be based on pfsense/opnsense paired with a openwrt device as the AP/switch.