I was trying to use a super smelter but when I put coal into a hopper minecart it disappears from the game  as if the hopper minecart is consuming the coal 

it disappears at a similar rate in which they can pick up items

there is nothing below the minecart and breaking it does not yield anything but the minecart itself

there is a hopper nearby it but the minecart is not on the block and the coal does not appear in it

it does not disappear when in other places and the same setup such as the one on the leftside