My lights to the rear of my 07 Tahoe work when the lights are on. My passenger side right brake light also works but my left side does not. I have already tried changing the bulbs and it still doesn’t work (flipping the lights inside the module didn’t work either). I check the fuses inside the cab of the Tahoe on the driver side and both fuses are still good.

could help me figure out what else could be wrong or what I might be missing?

 

Welcome from Florida. Check the socket and the wiring to the socket. Sometime the socket doesn't make a good connection to the bulb. Use a meter to see if there is voltage at the socket.