Reverse lights not working, the fuse is good?

It sounds like the gear range sensor is not working but to be sure here is the reverse light wiring diagrams so you can see how the system works and which wires to test for power, I did notice the BCM is involved so there is an outside change that is the issue.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Here is how to change out the gear range sensor/reverse light switch in the images below. Let us know what happens and please upload pictures or videos of the problem.