Thank you! Good idea about disabling mining while driving, I’ll do that. EDIT: Just implemented it in the development build! But, unfortunately, I can’t upload it before the voting period ends.
I intentionally made it so ore disappears if you don’t mine it over a cart. This way, you have to align the carts correctly, which is one of the core gameplay mechanics. I did consider that players may run out of ores this way, but if that happens, you can just surrender yourself to the zombies to restart the level. :-)