Lava disappear when it place under hopper block

When I place bucket of lava on the same block as hopper it dissaper. 

Expected result:If you try to place a lava on the same block as hopper it should not work or the hopper gonna lava lock like how it water lock with water. 

Actual result:The lava just disappear. 

How to Reproduce: 1.place a hopper

2. Then place try to place lava on the bottom of hopper block.