I think it's one of those issues that might take a while to sort out. I don't think that originally the developers on either side, Garmin or the light manufacturer imagined the layers of lights connecting to one device that we are having now. Though you might only have one light on your bike that can be controlled through your Garmin, the programming code for doing it probably has gotten quite complex.
I see my son fussing sometimes with the lights on his bike. He has several different types that he is controlling. Mostly though, it seems to work for him. But we have been held up a few minutes starting our ride while he plays with them. It's not a big concern, I figure they'll get better eventually.