I'm no IPv6 expert, so the following is only a speculation on my side, others may correct me: the DHCPv6 PD pool tells the Tik from where to delegate the prefixes via DHCPv6, whereas the remote IPv6 prefix pool is the one from which it assigns IPv6 addresses to the PPPoE clients themselves (i.e. to the interfaces representing the PPPoE tunnel at their end) via PPP, not via DHCPv6. So the fact that you have indicated nothing as remote IPv6 prefix pool may explain why the Asus is unhappy, although, as said, it actually should not need the address at all - a link-local one, which is added automatically, should be sufficient.
Instead of writing novels, post /export hide-sensitive. Use find&replace in your favourite text editor to systematically replace all occurrences of each public IP address potentially identifying you by a distinctive pattern such as my.public.ip.1.