Printable area mismatch from Lightroom to Epson 3880

I do not print to paper that often, but when I do, I am encountering a problem which I cannot quite figure out how to fix.  When I try to print a single 4x6 or 5x7 with my Epson 3880, only a corner of the image shows up within the printable area.  (It was able to handle 81/2 x 11 sheets just fine.)  I've have tried a number of different settings both in the LR dialogue and the printer dialogue to overcome this but was never able to come up with a solution.

I am using the printer for color management because of color mismatch issues I have had printing directly from LR (a subject for another day).

My workaround was to go into PS and print from there.  I suspect the issue may have to do with scaling, and there is a "Scale to fit Media" option which I found useful in the PS CC print dialogue.

I tried checking and unchecking "Zoom to Fill," but that did not resolve the problem.

I am also now noticing that I had the "Print Resolution" setting unchecked.  Could that be the problem?  If so, how do I identify the correct setting .  Although grayed out, it seems to be defaulted at 300 ppi.