Start the scene. Script MovePlane attached to plane object will wait few moments , that cube on top of it will stop entirely. Then plane will slowly start moving up. Cube will go through.
If you remove "if(Time.frameCount < 20) return;" from script, then cube will move with the plane.

Steps:
1) Create cube with rigidBody compenent.
2) Create something that will stop cube when it falls. For example plane.
3) After cube falls and stops, move the plane up.

Expected:
Cube will move up with the plane

Actual:
Cube goes through the plane and falls down.

NOTE:
Looks like every object will go through this cube while it is not moving. I've created another plane with the MovePlane script. And put it under first one. When Position.Y was -0.2 it went through the cube, when it was -1 it lifted the cube up (because where already falling when plane touched it)
If you set UseGravity to false, plane will go through the cube despite the cube's position (on the plane or above it). Seams that bug occures for objects that are not moving.