I created a new The Show account and the biggest difference I see is that under this account it shows as "Connected, Current Session" when I'm logged in. That's not the case when I'm logged into my normal Show account with my PS and XBOX accounts linked to it. That's probably a reason why you can't unlink and it takes you back to the login page -- they aren't synced up.
Just in case someone from the support/development team is reading these posts.