In your print dialog, I see you are using a “preset” called CPN, and your Lightroom settings are showing 0 margin. I have found Lightroom can get very flakey if using the printer driver presets. (some info I wrote some time ago is
here if you are interested)
It is much more reliable to leave the printer driver preset to default. A lightroom preset will be able to remember and recall perfectly every single setting of both the page setup and printer dialog boxes, as long as they don’t include a preset created within the epson dialog box/driver. Once you try to include that, all bets are off as to how reliable things will work.
I am not near a printer so I can’t test everything you describe, but there is certainly an oddity and the only thing that comes to mind is this preset is getting in the way. Try printing leaving this to default and then selecting all the other parameters. I believe this preset can remember things like margin size etc which may cause conflicts with Lightroom margins.
Were I trying to print what you described in the first post I would create a custom paper size just like you did. I would then Choose that paper size int he page setup, and choose the correct media choices in the Priunter dialog but leave that to “default”. I would then set my left and right margins in LR to be 1.375” and my top and bottom margins to be 1.875”. I would then save all that as a preset in LR ... as I mentioned all of the settings in the page setup, printer dialog and the actual LR settings will be recalled perfectly as long as you don’t use a printer preset inside the printer dialog box.
It’s a long shot, but you might want to try it.