Unfortunately it appears that getting WordPress going in IPv6 is a constant undertaking. Primary causes?
WordPress domains don’t support IPv6. And my DNS provider doesn’t fully support IPv6 at their DNS server (I can add AAAA records, but you can’t access the NS via IPv6).
So I end up having to create a few /etc/hosts entries to get plug-in updates and reference urls to work within WordPress. Additionally, pure IPv6 hosts would never be able to reach my domain because of lack of IPv6 at my DNS provider.
So if you are going this route, be ready to handhold your site for a while.