Migrating this from GitHub:
In the new DHCP Leases menu in the web interface, it should be possible to view, administer leases which have been manually specified in the dnsmasq config, which map multiple MAC Addresses to one IP address.
Since the format of these leases in the config file is an extra MAC address (or more) in the comma-separated list, the Pi-Hole web interface displays the 2nd MAC address as if it were the IP Address to be assigned.
Add extra MAC address(es) to the DHCP lease config file manually. View the web interface.
I'm not willing to submit this. The issue I'm reporting is obviously merely a straightforward oversight in the web interface design. No information in my log is necessary, nor is my spending the time just to make SURE that no sensitive information would get published along with it.