Hi Richard,
Are you modifying the Same Role in PRD & DEV. If the role is created based on SPRO project reference, System will not allow you to modify the menu, add/delete Tcode.
If it's same role and you are receiving "Not authorised" message, please check SU53 screenshot. As you have already compared your access in both system, I suggest to check User comparision is performed and profiles are Generated for all the roles assigned to you.
Regards,
Atul