Why don't you want to create accounts through a mobile app? I did the same for Instagram using swipe into DOB area.
In browser with a mobile user-agent I couldn't register.
Hi, my BAS Premium is still active with 25 days left, but I’ve been experiencing this issue since yesterday. How can I fix it? It was working before and suddenly this happened, I don’t understand why.

None of the ideas you gave worked, but thanks anyway. It resolved on its own, and if you encounter this issue, the solution is simply to wait — it gets fixed after 24 hours.