Discourse hub add site - "site was not found"

I have looked through all the previous discussions, no luck so far.

  1. I am on the latest version: 2.7.0.beta8

  2. SSL check seems okay: SSL Server Test: forum.australia.cmu.edu (Powered by Qualys SSL Labs)

  3. This link does respond, https://forum.australia.cmu.edu/site/basic-info.json

Any help will be appreciated.