Rear Running light issue GU433 Granite

All of those are on a 2nd switch, along with the 2 outside corner cab marker lights. Might seem like a dumb question, but do you have that switch turned on? I ask because if you aren't familiar with Macks, you may not realize there is a 2nd switch that needs to be turned on controlling the marker light circuit.
Assuming that switch is on, though, there is a fuse box on the firewall under the hood...should be a circuit breaker in there for the marker lights. Check that. If you're getting power to the circuit breaker, then check the relay for the same marker light circuit. For the longest time, the only way I had to turn my marker lights on and off was to insert a jumper wire in place of the relay...and pull it out to turn them off. Eventually, I replaced that fuse box. When I did that, I found a corroded connection on the plug that connects that box to the truck's electricals. Fixed that wire and it fixed my problem.

Hope that helps.