Sorry for delays there is a temporary forum server hiccup not allowing me to address all postings
I am trying to download a driver to emulate that printer but unsure If I will have the same duplex features/settings. I suggest you first test a small 4 page document (2 x double sided) to confirm it is not simply failing on a memory problem.
I see from the driver there are separate options for with and without duplex unit, so if you are using Manual I guess the auto handling is not installed.
My best suggestion is to use the same “Advanced” options as for printers without a duplex unit and print the odd and even pages as two sequential actions