Another thing I just remembered: Requiring 8 cells space between wind turbines is a major logic flaw, and results in another bug--placing multiple turbines next to each other is allowed until a least one of them is completely built. Likewise, we have to wait until it is completely dismantled before placing a new one.
Also, when setting an amount to always deliver, it delivers (amount + 1), instead. (Edited to add: It only seems to do this when neither drone is frozen; If there is only one active drone, it delivers the exact amount. This suggests that with two drones, the second one is also trying to fill the same order, and carrying one extra item.)