Hi
Sometimes SAP behaves weirdly as this is also a human written software you know 
If your issue has been resolved then you don't need to worry about background logic and programming. I'd suggest you to use the role ZABC. I believe this is authorization and I am also surprised to know that changing the authorization role is causing this issue.
Please share if the issue is resolved and if yes then close this discussion. If you want to know the technical background and logic then you better contact SAP directly on this which is not necessary i believe.
Thank$