Common enough problem. It's either a chip or a firmware issue. Here's what I've done:
When you have a cartridge of the same colour that reaches empty, and you're ready to toss it, swap its chip with that of the defective one. The busted cartridge should now read near end, and you can manually add 30cc as if it were. You may have to do this a few times, swapping chips as you go, but it'll let you get a better yield out of your stubborn defective carts.
Normally I'd raise hell with our supplier over this, but with the volume of ink we go through, it would be a waste of time to get a pick-up for the busted cart, and drop-off for a new one, when we could otherwise just cheat the printer and use the ink anyway.
A word of caution though, you need to keep an eye on the actual volume of ink in the cart (weighing, visual comparison, voodoo, whatever the hell), as you can actually run out of ink mid way through a print this way. Just takes common sense though. Don't use a really light cart on a long print, and don't leave it overnight, when you can't switch it.