Pipe bomb construction leaves empty space in backpack

[Dabir]

Build most of a pipe bomb in your backpack. Put something else in your backpack. Attach the timer/igniter assembly to the pipe bomb. The completed bomb is now on the floor, and items in your backpack have not reshuffled, leaving an empty space behind.

[Marquesas]

I don't get it, is this a visual or a functional glitch? I don't think anyone wants to bother with the former.

[Dabir]

I guess it's only a visual glitch, but it would be better if a pipe bomb being built in the backpack stayed there when you completed the last step instead of falling on the floor.