Redstone torches are disappearing when placed sideways in a powered block with a dust bellow the thorch

If you place a redstone torch sideways in a block, and then put a redstone dust bellow the torch, when you power the block, the torch will disappear. Then after it happens, you can remove the dust, and the placed torch will still disappear when you power the block, or even when you place a torch in the powered block.