Thanks for reporting this, it's helpful. I found the issue, and we'll fix it.  Basically, you had two accounts in the system (one of which was created automatically).  You were logged in as one, accepted the invite, tried to create a profile but couldn't because the email was already registered, then you logged out and logged in as the other which didn't have an invitation.

We've merged the two accounts, and are working on a way to automatically detect this in the future.

In general, this issue affects a small number of users, so if anyone runs into any problems, email [email protected] and we'll sort you out.