Unexpectedly exiting Collider that is moved along with the player

Here’s my problem and the thing i do not understand.

I got an elevator with the following parts ( see screenshot )

  • Platform - Empty object, with a Scale of 1.0, which is moved by the elevator script
  • Platform.Physical - the visible mesh and the ground collider
  • Platform.Attach - trigger-collider that makes the player a child of itself
  • The player is a Unity.CharacterController moved in Update
  • The elevator script moves the Platform in Update

I got debug lines showing, that the player character while being a child of Platform.Attached is moved by the exact amount that the whole platform is moved.
This works flawlessly while moving upwards, but moving downwards, the player OnTriggerExits the attach-collider.
The player is a CHILD of the collider and has ZERO movement in local space relative to the collider, they are both moved by the parent of the collider. Yet the OnTriggerExit happens.

Update: The coordinates logged after moving both objects in Update and then in the next physics

a) same coordinates → TriggerStay
b) same coordinates → Trigger Exit

what the magic?^^


So obviously moving them both as parent and child works fine, the distance between them stays the same, yet one time, the collision is TriggerStay and one time it’s TriggerExit