Discourse doesn't redirect to return_sso_url after user logs in on private site

[simon]

After re-reading your post though, I’m wondering if you’re testing using username+password logins instead of twitter logins. We have password logins turned off and the only way you can login to our discourse is through twitter. That might explain the differences.

Yes, that’s it! I can reproduce the problem with the wp-discourse plugin when I use Facebook login. I’ll look into what’s going on.