laser printer not printing double-sided

[Laurie-UEP]

My Laser Jet Pro M402dw stopped printing auto-duplex shortly after a Windows 10 upgrade.  It may have been a coincidence but it printed fine 20 minutes before that.   

It prints fine single sided.  However, I need to press "ok" for it to recognize paper tray 2.   When I set it to print double sided, I get the same message about Load Tray 1  and then "Set Up Memo Stored Jobs."  followed by message about the rear USB drive with at least 16 GB available.  

I've uninstalled and reinstalled the driver several times.  Rebooted and uplugged and replugged the printer many times.  I've checked the settings and all say that the duplex is "installed" and the paper tray is set to Tray 2.  

[Repairatrooper]

If you are getting a prompt about insert a 16gb drive then your driver may be set for job storage. It is quite possible that in the process of upgrading windows installed a Microsoft driver and replaced your previous driver. The most reliable driver to use is the HP Universal Print Driver. The reason you have to push ok is that your driver or program is looking for a paper size or type that is not installed or set on the printer. On your PC fo to control panel>devices and printers and then right click on the icon for your printer and select printer properties. Then click on the device settings tab and scroll down to installable options and make sure it shows that the duplex unit is installed. If it shows no duplex unit installed, change the option to show duplex installed.