I used to have no problem printing borderless using Mac 10.11, LR and Pro 100.
Now, when I print borderless I get a sliver of white on the left and the bottom on a landscape orientation print.
I've chosen borderless paper in page set up.
I've chosen Zoom to Fill
The Cell size is maximum
All the margins in the LR Print module are zero.
What else might I try?
Thanks for your consideration.
In the the Print Settings dialog, under Page Layout Settings be sure that Expansion is set to Max. The white border occurs when Expansion is set to Min and the paper alignment in the printer is not exactly perfect. The expansion setting causes the print to expand slightly to be larger than the paper, thus eliminating the white sliver of a border.