IgnoreCollision affecting children & unrelated objects when it should'nt ?

I've encountered what I think is a bug - sent a bug report about 1 week ago but I thought Id mention it here.

Scene :

• One moving cube "CubeA", one large flat cube for the ground "Base", one trigger volume "Trigger" child of "Base", one non-moving cube "CubeB" already inside "Trigger".

• "Trigger" has a script monitoring objects entering and exiting its volume.

• When "CubeA" enters "Trigger", a script calls an IgnoreCollision between "CubeA" and "Base".

Observation :

• When the "IgnoreCollision" is called between "CubeA" and "Base", "Trigger" fires exit and enter events for the object "CubeB" altough it didnt move at all.

It reacts as if "Trigger" (children of "Base") was switched off then on again, when it should simply ignore collisions with "CubeA".

Expected Behavior :

• "CubeB" and "Trigger" interactions should not be affected by a command to ignore collisions between "CubeA" and "Base" or its children.

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I can understand it could be on purpose that ignoring collision from the parent would ignore collision from the children too, but im pretty sure it shouldnt affect events of a child trigger with unrelated objects.

Can anyone confirm this is not the intended behavior ? Its quite a problem for me as in the actual project this behavior causes a logic loop that is quite tricky to avoid in a clean way.