I have a WorkCentre 6505DN. I don't remember when it started, but it won't print duplex in windows 10, 32- or 64-bit. When I was running Windows Server 2016 it printed Duplex fine. I have since gotten a new Windows 10 64-bit PC and it won't print Duplex. I tried printing Duplex on three different Windows 10 systems and none of them print Duplex.
I cheked the Printer Preferences on all three Windows 10 Systems and they are set to "Flip on Long Edge". The Device Settings on all three Windows 10 systems shows "Printer Duplex Unit: Installed".
When I restart the printer, the configuration sheet that comes out is printed on both sides, so I know Duplex will work.
I have the most recent Firmware installed (95.61).
How do I get Duplex printing working in Windows 10?