Does anyone know why loading a source transaction record in SuiteScript would result in an error 'Permission Violation: You need the "Lists -> Custom Record tab" permission to access this page' (even though that permission was granted to the role in use)?

Is the script running as a different role?

It's a UE deployment running under a custom role that has that permission added

Is there a custom record associated with the source transaction that uses "Use Permission List" for it's Access Type? I'm not sure if the Role's permission would override that. Just a thought.

Could be, I will check into that