The forklift has a minimum capacity of 3 planks, so it won’t pick up lumber until this amount is available. This is how the system is designed and not a bug.

When you upgrade the forklift, its capacity increases, and it will pick up larger loads based on the new limit.

However, if you receive an order that requires only 1 plank, the forklift will still pick it up. Orders always have priority, even if the amount is lower than the forklift’s normal capacity.

So everything you’re seeing is expected behavior, and the forklift is working correctly according to the game rules.