回答“Full cartridge but ink not printing.”I saw a comment somewhere in this thread, tried it: "stick a clear tape over the contacts of the ink cartridge". It's really odd, but putting a clear tape over the contacts of the black ink cartridge (and left it there) worked! My printer (HP DeskJet Ink Advantage 1115) now prints the "missing black ink" that I needed to see. Perhaps I'll just remove the clear tape next time. P.S. Before I arrived at this page, I was really frustrated since I’ve already spent an hour or so cleaning and aligning the cartridges, printed lots of test sheets, removed the ink cartridges and cleaned them using a Q-tip/cotton buds, browsed different options from HP website, etc. Stumbling upon this thread was a lifesaver.