Two-sided printing is not working
There are two uploaded images.
One is the advanced preferences setting showing that the duplex flag for the printer is correctly set to two-sided printing.
The other is the settings on the Print menu (CTRL + P) with the selection of two-sided printing. However, there are 5 single pages and it was not halved to 3 pages. Switching between single-sided printing and two-sided printing does not change the amount of pages printed number.
If I print anyways, it comes out single sided. I've refreshed my settings, reinstalled Firefox, ran in safe mode and it still does not work. However, in a different browsers and applications, the two-sided printing work correctly.
What is wrong with the two-sided printing?