Trying to print to (custom) 13x38 in paper. The print only prints a 10x7 piece in the middle. I've set up a custom paper size, loaded a profile from the paper suppler (Red River), tried network and direct printing, turned off "check paper size" on the printer's LCD. Nothing changes the behavior except the rear loader never works at all.
Which version of Lightroom are you using?
What is the Cell size and Margins selected in Lightroom
What happens if you Print with Default Page size or create a Page size of your own?Does that work fine?