Headlights work, actual brake lights work, license plate lights work (constant on), and turn signals work but rear running lights will not illuminate.

Cab clearance lights are also not coming on.

When I plug in my trailer, only the trailer brake works, no lights whatsoever.

I have had LEDs in all these places for several months with no issues.

I cannot locate a loose connection or burnt fuse.

If I only had to drive the truck during the day with no trailer, maybe not such a big issue, but I need to pull a trailer and have working rear running lights due to work and such.

Any known issues with the BCM or something on this?

I find it highly odd most functions still work, except for the trailer.

I could not locate anything on this partial functionality and am not sure what the heck else to look at.

Any advice or direction is much appreciated!