Touching compound collider breaks trigger

Hi,

I've got two characters and place another collider + rigidbody centered between them. My position update looks like

 void FixedUpdate() {        
     // position segment 
     rigidbody.MovePosition((startAnchor.point + endAnchor.point) * 0.5f);
 }

Whenever one character enters a trigger and touches another collider inside, the character doesn't trigger OnTriggerExit() correctly anymore. (It doesn't have to be a compound collider like in the video, a normal collider + rigidbody does the trick, too).

Have a look at the video of what is happening.

Disabling the centered GameObject or not touching another collider inside and everything works fine.

I spend more than a day on this and am really lost here. Thanks for your help guys :-)