This might be related to https://community.auth0.com/questions/12878/allowed-web-origins-no-longer-accepts-localhost-or but I am posting it separately as it is different in the host part of the origin isn’t explicitly localhost.
We use hosts of the form http://sitename.127.0.0.1.xip.io:9000/ in our test environment. The UI accepts these as callback URLs but not origins. I get a message that said "The following URLs are invalid for the Web Origins property: http://sitename.127.0.0.1.xip.io:9000/
[Note that I tried to post this once already and got myself to a an auth0 page where I got the auth0 oops page. So if this posting gets duplicated I am sorry.]