Hello helppleseandthanks,
Sounds like you have tried everything already, so it would be a hardware escalation: 1-800-821-2797.
The double sided scanning comes out with black pages on the underside. I already cleaned the printer, unplugged/turned off and did the same items listed in a previous forum question (https://forum.support.xerox.com/t5/Copying-Faxing-Scanning/Double-sided-scanning-all-black-page-scan...), but I can't figure this out. I also downloaded/installed the Feb 2022 firmware update.