This is resolved. So my ISP had actually CHANGED the way they doing ipv6. I was supposed to and had previously setup two pppoe interfaces and forgotten all about this. They changed which broke things. I contacted them and they provided new instructions, now the documented standard OpenWRT ipv6 config with @wan works perfectly.
I still don't understand why I was not getting a link local address but afterwards suddenly started to get one. The ISP said they needed to enable something on their end ...but I cannot understand how that prevented me getting a link local. Must be some special PPPOE thing.. Thanks all for your help.