If i use a shear on a cropstick it does not drop neither the normal product neither the block. For example, if I use shears on cactus block I expect it drop a cactus green or a cactus block, no drop received.

Crop growth state become updated.

Shears start working from higher growth levels only, whats the gain on the cactus

@InfinityRaider so it means shears not working unless cactus has big gain level? but why "ungrow" the plant then?

Its a harvest attempt, it just drops the amount of fruits/2, because flowers give you twice the dye.
And 1/2 = 0.