I've wondered if LED lights combined with modern electronic ridden vehicles aren't a little more sensitive to issues than older vehicles with incandescent lights.
I had an issue picking up my trailer right at ETI. Checked the trailer lights and there were issues. They put their tester on the trailer and all was well.
Drove to the Ford dealer faking brake lights by turning my headlights off and on.
Turned out to be a special fuse for trailer lights, who knew. Since then they've worked flawlessly.
I guess the moral of the story is don't take anything for granted even with a new vehicle and a new trailer. Gremlins happen.