I have been using LR for close to 10 years and have ever had this problem. I cannot get a photo to print in landscape. If i select landscape on in the page setup module it appears as portrait. When I select portrait I get landscape. I am using a custom paper size of 14.8155 inch x 11 inches. No matter what combo I chose nothing prints correctly. All drivers are up to date. Mac Pro 2013 El Capitan.I have spent over 3 hours troubleshooting :-(. Thanks!
Might be a El Capitan printing system bug. Have you tried specifying the custom size as 11x14.8155? It seems it really wants the long side to be defined as the height for the landscape and portrait buttons in the page setup to behave correctly.
Yeah just tested it. If in the custom size dialog you set the length to the shorter dimension and width to the longer dimension, it gets confused and the page orientation button in page setup is reversed. Looks like a silly peculiarity of the Mac OS X printing system. It should just correct you and take the longest dimension as the length even if you typed it into the width field.