@dae Your mention of Ank trying to bind 127.0.0.1:0 gave me an idea that solved the issue. Sometime ago I had created a network service on Loopback in order to create an ad hoc peer-to-peer computer network.
Steps to resolve:
- At command line delete the service using
networksetup -deletepppoeservice <service name> - Delete
Library/Application Support/Anki2 - Reboot
- Open Anki and follow setup
Thank you for all your help!