Shift-right clicking a drawer with an empty hand to bring up the GUI results in blocks appearing to vanish. This only happens when connected to a dedicated server, and not in single player. Also, the drawer needs at least 128 items stored inside. This is purely visual, since you can still withdraw blocks, and when you place one back in, it restores it to normal.

Also I broke a drawer to move it slightly and none of the items inside dropped. The drawer itself and the upgrades did drop, however. Not sure if this is an intended change for performance reasons (lots of item entities on a fully upgraded drawer), but I don't see any mention of it anywhere so I thought I'd mention it.

Forge 2153, Drawers 4.0.1, Chameleon 3.0.0