I have this too, I came to the forum hoping to find out what the heck is going on. It just is a loop, when I select the little profile button on the bottom right, it doesn't display my pfp and it basically says to sign in. When I click sign in, it takes me to the 'heres what you can do with your account page.
I can sign in to the sync site fine.
I know i know it updated recently but not exactly how long ago.