The scan feature on my HP officejet pro 8720 seems to work as far as it scans the docs either on the flat tray or the doc feeder tray. The scans look perfect when they appear on the screen. However, when they are saved, they look different and when you print one, it is all jumbled up
I faced the same issue and followed these steps mentioned by a friend of mine and it worked for me. You can try these too and let me know if it helped you too 🙂
First open the HP Solution Center software, click on the Settings, select Printer Toolbox, under the Printer Services tab> check the Align the Printer Cartridges and click Align> that will align your printer cartridges. Now take the alignment page and place the alignment page on the scanner glass with the printed side down and press the scan button on the printer control panel. The printer will now scan the alignment page and align the cartridges. Once the alignment is successful , press done.