I would guess your other cars are a different number of stops so the top floor is a different floor than this car. STU and STD are used to signal step up or step down when the car is running but when at the floor they’re used for binary position. I’ve seen this at one floor from a broken magnet that’s halves have spread apart but not your problem if it happens at other floors. It does sound like your dead zone might just be set too tight but if level up and level down aren’t used what’s actually triggering the relevel? I’ve never worked on one of these valves before. Does it store a floor table and trigger its own relevel?