It seems that when an object is a sensor local preCollision does not fire properly althoug in case of normal collisions all runs ok.
You can test this behaviour easily in Collision Detection sample code included in Corona (Corona SDK\Sample Code\Physics\CollisionDetection) changing second crate to sensor in line 35:
physics.addBody( crate2, { density=3.0, friction=0.5, bounce=0.3, isSensor=true } )
When you do that preCollision detection for crate2 stops to fire.
[import]uid: 122411 topic_id: 28119 reply_id: 328119[/import]