iTunes Store: Can't access Apple Account
I've been unable to sign in through the iTunes Store (version 12.13.10.3) and make purchases for several days, getting responses like an unknown error 301 and 'sign in to your Apple Account is not available right now'. No issue signing into my account on platforms other than specifically iTunes, and there are no reported outages with the service, so it's not clear what I'm meant to do to resolve the issue. I've tried common fixes like changing my password, troubleshooting my internet connection, and so on.