MF465dw ll .. Win 11 Pro 25H2 .. I recently had to change my Default Printer from the PDF utility (not My choice) back to my Canon Print Driver. Surely not the cause ... but something removed 2-Sided Print from my Print choices. Most How-To-Fix's show different screens in Windows than what I have so you'll may have to interpolate for your Windows (former W10 was much different) ....
In W11 25H2 my FIX was via ... Control Panel/ Hardware-Sound/ Devices-Printers/ Printers-Scanners/ CanonMF460...UFR ll / Printer Properties/ Device Settings Tab ... on the far left the 2-sided Printing Box was UNchkd ... via something recent, Not me... Chking the Box restored 2-Sided choices in the Print drop-dn offerings. FYI...
