stat.mineBlock.minecraft.grass does not register when mining grass

when using the stat.mineBlock.minecraft.grass in a scoreboard it does not add the points to the scoreboard when mining in survival

IF HOWEVER you use stat.mineBlock.minecraft.dirt it counts both dirt and grass being mined.

to replicate:
1. /scoreboard objectives add grass stat.mineBlock.minecraft.grass
2. /scoreboard objectives add grass stat.mineBlock.minecraft.dirt
3. /scoreboard objectives setdisplay sidebar grass
4. /gamemode 0

then mine grass in survival

5. /scoreboard objectives setdisplay sidebar dirt

then mine dirt in survival