Kids Messenger won’t work

We've recently had to resign into MK and when going to log into Messenger Kids with my account we click on "Authorise Device" and then the app logs out and loops back to the login page.

We've also tried downloading MK on our phones and get the same behaviour.

She was previously logged into MK on her old device, but no idea why we're unable to log into the account anymore. just loops and loops back to “authorize device” ? kids are going crazy not having it