I had something similar happen and it turned out that I hadn't set the Output Paper to be the "Same as Paper Size" on the Page Layout tab of Printer Properties. HTH
Thanks for your reply. I'll check that. Do you mean "let the Output Paper in LIghtroom in the left hand panel? I had set that up as custom 13x19 but I'll check that again.
Sent from my iPad
Sorry, I wasn't working in Lightroom at the time, but in LR, go to [Page Setup] (lower left corner) and when [Printer Setup] comes up, <click> on [Properties]
I'm working on a Mac. I suspect Properties is on a Windows machine. In the meantime, I re entered the paper size and the problem has disappeared. Thanks for your help.