It's now seven days since I can not use the WebApp through the site. I can login on the game (Xbox Series X), I can login on the mobile Companion App. I can list players on the market on both. I tri...
For me what solved it is connecting to the account on console, if you have multiple users (aka personas) connected to your account make sure to connect to the other consoles as well, because your default user might be the one on the other console.
So for me I always play on PC, but the selected user was my XBOX one, so I had to connect to my XBOX user to fix it.
I think it's related to the news pop ups when you log in, the web app doesn't support more than 1-2, so every time that there are multiple news pop ups it stops working, of course no one in EA even cares to look at it, during TOTY there were thousands of people that failed logging in because it added multiple news pop ups, still, no one cares, no monitors, no one to contact, don't remember the last time I saw a company that cares that little about it product and customers.