Two of my dogs flat out refuse to go out after dark. The third stands at the door, looks all around then ventures out just far enough to pee. All are 40 lbs and up. I have a theory that might explain similar issues for other owners. The last time all three and I went out they were staring up at the night sky. No sign of fear but intent on the sky. I suspect the neighborhood Great Horned Owl was circling. A handler at a Birds of Prey show told me once the owls will follow along hoping you’ll stir up some mice for them.
So, not so much a question as a theory I hope helps others. And a big reason to not let small dogs out alone at night.