In Acrobat, I can print both sides on letter-size paper in Portrait mode, but not in Landscape mode.

The title about covers it. I've gone over the available options many times, in many combinations, but it just is not possible to print double-sided (duplex) on a duplex printer if the material to be printed is not in portrait mode. It doesn't make sense to me, but that's the way it is. If anybody there knows different, please  fill me in. I know enough to avoid the "print both sides" checkbox on the acrobat print interface-I always set it up in the printer interface. Either way, after a few years (and a ream of paper) of trying, I have never been able to print both sides in landscape mode, using short-edge binding. Or NOT using it.

As I said, if anybody there knows different, please  fill me in.