The peer config for Wireguard in beta 3 appears to accept IPv6 addresses for the endpoint-address var, but the resulting peer object's endpoint-address content is empty. This occurs in CLI and Web.
IPv6 addresses either need to be prevented from being entered, or parsed properly to the Wireguard tools.
Naturally, I would be very grateful if you could allow Wireguard to connect to peers via IPv6.
Let me know if you need further information.