hunch about air moving clothes is probably right but sometimes the hangers only twitch a millimeter and that is enough. I actually had to immobilize the row of shirts. Two zip ties around the rod with a small gap creates a corral so the hangers cannot slide and sway. can also clip a couple of hangers together near the hook to dampen motion.
Then point the sensor down the wall rather than across the rod. I left a tiny sliver of black tape on the outer edge of the lens to keep it from seeing the door gap. Works great.
