Try putting a prop_static in your map with this model: “models/props_c17/lamp_standard_off01.mdl”. The info panel shows that this can be used as physics or static, but works only if made prop_physics; a lot of other models have the same problem! Why?
I don’t know why it happens, but if u need them to work like static just disable the motion in the flags tab.
I make mine dynamic override when this happens.