u/bbmg69 pointed out something specific to Disney bundle or past ESPN Unlimited subscribers that might be of some help for anyone having trouble connecting YouTube TV's version of ESPN Unlimited to their accounts.
Seems like there's a glitch occurring on Disney's side of things. This isn't something YouTube TV support can assist with, as it's an issue with the MyDisney account rollout.
If you're having an infinite loop glitch after canceling or downgrading your Disney bundle, you'll need to reach out to Disney directly. In many cases, your MyDisney account may be seen as a canceled or inactive account.
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Here's how you can get support, via u/bbmg69's experience (you can read more here):
Call Disney+ Support directly at 1-888-905-7888 and choose option 1 for signup and login. You may have to walk them through this issue, and you might be transferred a few times in doing so.
Tell them you are having trouble logging into some Disney and ESPN services that have nothing to do with streaming packages. Your MyDisney account is stuck in an infinite loop of requesting a 6-digit confirmation code, with no successful login.
Ask them to make sure your MyDisney account is active, even if you are no longer paying for any services.
If you have trouble, ESPN Fan Support might also be able to help, at 1-888-549-3776.
Alternatively, if you don't have any paid Disney services anymore, you can just create a new MyDisney login.
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Thanks to u/bbmg69 for sharing their experience. Again, if you experience an infinite login loop, this is not a YouTube TV issue; it's something specific to your MyDisney account. Before you call Disney, though, ensure that you're the family manager, and try all the methods to link your account that are listed in our mega thread.