Hi,
The Pi-Hold I have set up on Ubuntu 16.04 Server 64-bit does not display the system's IPv6 address on the dashboard. The blocking features of Pi-Hole over IPv6 work correctly though. I wonder if it is due to that fact that the Ipv6 address is assigned via DHCPv6. Maybe mot people probably use SLAAC or Static IPv6 addressing.
Let me know what I can do to investigate this further.
Thanks in advance!