Why don't all DHCPv6 leases get added to DNS?

In the latest trunk build (SNAPSHOT, r3580-e8871d9) I've noticed that I can now see automatically configured hosts in the DHCPv6 hosts list in Luci. This is very cool as prior I could only see the hosts that I had assigned a static hostname to.

Anyway, the problem I'm having is that I can see the host names in Luci but I can't actually look them up via nslookup. The only hosts I can look up are those that I have defined a static IPv4 hostname for (from what I can see the DHCP server assigns an IPv6 address based on the last octet of the reserved IPv4 address).

Any DHCPv4 clients can all be looked up (nslookup) and appear to be reserved properly but the same isn't happening with IPv6 clients. Why is that? The system is obviously aware that they have a lease out there but it won't let me look up the v6 address of the hosts.