So are you saying switching off 2FA will resolve the issue? If so, how do I do that? I do have 2FA on as when I switch or log in to the account on any other device, I do get a code sent to my mobile. I can’t remember ever having activated this, however, I thought it was done an Apple’s side and was mandatory.
I have just had the issue happen again when I switched from my DE to US account. It was still showing the DE store and I had to log out and back into the store on my Apple TV. Hasn’t happened for weeks so I thought I’d fixed it. Annoyingly I reinstalled test flight just a matter of days ago so it does again make me wonder if the issue is somehow linked to a sandbox account after all as the issue was gone for weeks now and suddenly returned after I reinstalled test flight.