I think there are huge bugs around this, considering that I have had this happen a lot myself but also mentioned in the sign up to my own instance - people specifically saying that they couldn't sign up on other instances due to spinning forever on signing up.
All that is needed is error handling here. Is the email not being sent? Is something else happening? No info at all to the user.
I suspect email since when I either turned it off or configured it correctly, things seem to work.