Thanks for the screenshots.
Just to confirm when you were banking, are you expecting it to only deposit and not withdraw anything? This is how it is setup in your screenshots.
If you want it to withdraw stuff, it has to be on the list to the right. Best way to do this is to set up your inventory and then click 'Copy Inventory'
I also noticed it wasnt setup to eat food in this screenshot
You need to tick 'Eat Food?' if you didn't. This might be why it died at barbarians
The cannon definitely shouldn't behave like that, was there any message in chat saying the cannon broke or is empty? Last I tested cannon it was working fine