Another common issue could be a clogged printhead. Over time, ink or toner residue can accumulate and block the nozzles, preventing the black ink from being properly distributed on the page. In this case, you can try running the printhead cleaning utility through your printer's control panel or printer software. Follow the instructions provided by HP to perform the cleaning process and see if it resolves the “Hp Printer Not Printing Black On Both Sides Of Pages” issue.