I'm aware. Unfortunately I cannot tell how an item was spawned, whether by mining a rock, items spilled on the ground, or if the robots are actually mining. It's a small downside, but ultimately this prevents robots from being a way to bypass ores with excessively long mining times.
I could add an extra check if ore is nearby, but then the last bit of ore would have no mining time and checking this every ore item picked up could create a a significant performance impact.
