Huh. Well... The only other thing I can think of is... is something causing your network to flicker on and off when you try to craft something, like a power outage or a dark cable being toggled? Either would cancel any crafting jobs- do you have just barely enough power flowing to your network to keep it running when it's doing nothing, but not enough to run the MAC? If you stand somewhere where you can see the front of one of your ME devices (another terminal, for instance) out of the side of your screen while you interact with your terminal, does the other device flicker?I've had issues with this before. All my recipes in the MAC use Minecraft Glass, Minecraft Jungle Planks, Minecraft Cobblestone, and Minecraft Sticks just for that reason. Unfortunately, i can say that this isn't the issue. I wish it were something this simple and obvious.
Perhaps more importantly, what does you Crafting Monitor say after you've requested a piston? Does it say you're missing anything, or does it show that the job got cancelled?