Hp envy 6020, after running out of black ink, after replacing can't print black

[Mrrubbs]

After replacing both supplied inks in my envy 6020 printer, with freshly opened hp supplied instant ink cartridges, I cannot print in black. I've tried several cleaning cycles, used over 30sheets paper, tried all sorts of printouts including calibration sheet, they are All missing black. I've reseated cartridges, cleaned contacts, several times..no luck. Is there a possibility that because I ran out of ink it's stuck in backup mode, is it possible to reset this? I'm on latest firmware for printer. Have used wet tissue to confirm there is ink in the black cartridge, just running out of ideas.

[Mrrubbs]

Further info, tried b/w scan of document, goes through as if scanning, printout blank,do same with colour copy, I get a reasonable attempt of a printed copy(without any black..just simulated greys). Printers been switched of for many minutes, switched back on..no change hours later! Any help..please!