There was this similar post about a year ago:

https://board.moparts.org/ubbthreads/show...rue#Post3497079

You can "test" the switch to see if the "reverse" portion of the Neutral-Safety/Backup Switch is functional.

Beyond that, the wiring (and you have checked the fuse too) and the light-bulbs/sockets (no corrosion, filament intact, etc) and beyond that it could be the contact-arm inside the transmission.

Process of elimination. Funny how sometimes it turns out to be something like corrosion, etc.

Good Luck.