All of my printer orientations are in landscape mode, because 90 percent of my photos are landscape format and I like to see the image laid out horizontally in the LR print module. I will do some experimenting today to see if I can get the printer to repeat the truncation of the image. BTW is not only prints half height, but it actually cuts off the top half of the image, so I don't think it is a scaling issue. I will try to find the scale check box. I am not good at grabbing screen shots, sizing them for display, etc. but I will try if I get the printer to repeat the problem.
If you are printing in landscape mode, you should not use one of the size presets listed in the dialog box. You have to create a custom paper size that matches the orientation of the paper as you put it into the machine.
The printer must know the width of the paper you are inserting, as well as the length. If you chooose something like Super A3/B, you are telling the printer that you are inserting a sheet of paper that is 13" wide and 19" long. It doesn't matter what the image orientation is at all, the paper size is all about what you are inserting in the printer. If you put the paper in landscape orientation but don't create a custom paper size for it, you will constantly have problems with half printed images, or even worse, things like 1" strip in in a corner. Sometimes it seems to work, but more often than not you get exactly what you are describing.
This is a common problem and I see it happen all of the time as people relate the image orientation of what they are printing to the piece of paper.
If you want to print with the paper in landscape orientation, you can easily do it (I do it all of the time), using the Super A3/B example you would create a custom paper size of 19" in width and 13" in length, either with default borders or if you are creating borders in LR, then with .0" borders. Note now that your "landscape" image is now in portrait orientation in relationship to the paper that you are printing. So the checkbox for orientation must be set to portrait.
I have printed thousands of sheets like this with no issues.
BTW, In Lightroom if you have the paper size/orientations correct the image will not appear sideways. In fact if the image is side ways (unless you've forced it to be rotated) that is a clue that you probably have the wrong orientation checkbox selected. You do not need to print with the paper horizontal to see your landscape image correctly in the LR print module. L
If I print a landscape image to a 13x19" orientated piece of paper in the printer, and i have the landscape checkbox selected, the paper preview will appear horizontally in lightroom and the image will be oriented correctly- it will not be sideways even though that is the way the sheet of paper is inserted into the printer. If I print a landscape image to a 19x13" piece of paper placed in the printer (and I have created/selected an corresponding custom paper size), and I have the portrait checkbox selected (because in relationship to the piece of paper it is now a portrait orientation and does not need rotated) it will appear identical. Click the opposite orientation checkbox in both of those scenarios and the paper preview will now be vertical with the image sideways - definitely a clue something is amiss.