Coarse Dirt cannot be tilled if a block is ontop of it

1. Place Coarse Dirt
2. Place any block on top of it
3. Fail to transform Coarse Dirt into Dirt (Stone, Fence Post, Any flower, Cob Webs, Tall Grass, Iron Bars, Anvil, Flower Pot, and Mob Head have all be tested and do not let you till the ground to transform it into Dirt)