Hello SRBC0550,
Thanks for posting on the Apple Support Communities. I understand that you're not able to sign into your Apple ID in your primary user account, but on another user account you can sign into the Apple ID just fine.
Assuming that you are signing into the Apple ID using System Preferences, the issue is user-specific to your account. Most specifically the Keychain Access, where your login information gets stored at. The Apple ID and password may be prevented from saving in that specific user, resulting in a permissions issue with your Keychain.
I recommend that you accomplish one of the following steps:
- Create a new user and migrate your data to it.
- Attempt to resolve the permissions issue.
- Turn off iCloud Keychain (if enabled) and reset Keychain Access.