I've invited a new user to join our team in a projet and despite being signed in, he can't be assigned to any story card. Searching different forums highlighted that this usually happens when the user has never signed in yet. I've checked in the admin panel and it is written that he has "never signed in". After talking back and forth we sat together and signed him in on my computer. I'm literally in his account and it still says he never signed in... We tried setting him up again with a different account and we are running in the exact same issue...
He has access to seeing the project, which only a signed-in account in our organization can access.
At this point, I'm stumped..