Have almost the same issue as my custom trail boss has been in and out of the dealership over the past three months. My situation is a little different, as my truck didn’t have fog light when I picked it up. I put my fog lights on my custom thru the Chevy parts department (obviously with the parts they ordered) a few weeks after I owned it. The majority of the time the indicator light comes on but the fog lights do not. Luckily my dealer has been very accommodating but it is a hassle in general. The fog lights turn on every once in a while but they are completely unreliable. The truck is back at dealer now for the 4th time regarding this issue but due to the strike, they only recently received the Module and new fog light kit that they are going to replace everything and start over.
Hopefully my truck is ready today or Monday but if I have any answer to this mystery I will post it here.