Double-sided printing mode grayed out

I have had the same printer for 5 years or so. Canon MF733CDW laser with duplex printing. Suddenly, there is no box in the driver to indicate the printer has duplex printing capabilities. I am guessing Pages is looking for that flag?

Other apps like Word and Acrobat print duplex just fine. Just Pages shows the option grayed out. I suspect other apps too, but I haven't checked every app.

Any ideas?

Thanks

Stan