I have a MacBook Air and using a Canon ip2700 updated etc. I am trying to print a 4x6 picture and it just won't do it. It only prints part of it or just a strip down at the bottom. I have set the size in the Canon printer specs and it will not work.
Can you post a screen-clip of your settings in the Print Layout panel-
Some general advice-
Totally ignore the default Print templates supplied in LR.
Check your printer setup details and properties carefully for the correct paper size and type.
Check that the sliders in the LR Layout panel are giving minimum margins and maximum cell size.
eg. my Epson setup for 6x4inch-