Hi Tracey K,
Welcome to Microsoft Community and we regret the inconvenience caused to you.
Is your printer installed on one computer to be shared with other computers over the network or on a server? Is the duplex disabling feature enabled on main computer?
I think this may be caused by 2 reasons.
1.One is the driver, based on my experience you can replace it with a universal driver and check again.
2.I recommend trying a clean boot which starts Windows with a minimal set of drivers and startup programs. It can be used to determine whether a background service or program is interfering or causing a problem.
These steps of "clean boot" might look complicated at first glance. However, to avoid any trouble for you, please follow them in order and step-by-step. Of course see if it works in safe mode with network too.
If issue still persists this may be a compatibility issue between a specific print driver and Windows 11. If you install the printer in Windows 11 and restart the computer, will this feature still be disabled?
Thanks for your patience and wish you everything as well.
Best regards
Nice - MSFT | Microsoft Community Support Specialist