Minecart with hopper vacuums up items from composter even if the cart is full.

Minecart with hopper vacuums up items from composter even if the cart is fully filled by bonemeals. And the bonemeal newly created by composter appears to have disappeared.
This will only occur when the item is vacuums directly from the composter. (In the following picture, it occurs in the left case but not in the right case.)