For proper stats to be displayed on the dashboard you have to see if its possible to configure the Amahi DHCP service to push the Pi-hole IP address to its clients for DNS resolution (methode 1 and also the link that was posted in the first reply on top):
And activate Conditional forwarding so Pi-hole can lookup all names that are local to your network against the Amahi DNS service.
EDIT: And test with nslookup eg:
nslookup <HOSTNAME_LOCAL_NETWORK> <AMAHI_IP>
&
nslookup <HOSTNAME_LOCAL_NETWORK> <PIHOLE_IP>