I’ve discovered an issue with the Epson driver and Lightroom (Classic). It appears to be a Lightroom issue because it's only happening when I print through Lightroom, thus far.
Here's the situation:
Below is screen capture of my Lightroom Classic settings and my Printer driver settings. At first glance it appears that everything is fine and I will receive a portrait aspect print on 13 x 19 paper out of my P800 or P8000.
Below is what comes out on the printer end. (The image is only cut short because I trashed the job part way through to save ink).
Below is what I've identified as the problem and then the fix.
When a present is made via either a custom paper size or paper/ink preferences, that preset will forever be stuck in whatever orientation (landscape or portrait) that you set up your page in. You have to get your printer driver to go back to the default setting - not just by selecting default settings - but by selecting, for instance, a totally different paper size and then selecting the Printer button in Lightroom, as if you're going to print. Then you can begin again with another setup and have your print turn out correctly.
When the configuration above is printed (note the "preview" page orientation is now in portrait, versus the first screen capture page orientation "preview" which was in landscape) the print comes out correctly, as seen below.
This is a bug and I began encountering it after the Adobe changes to Lightroom in October 2017. Epson advanced tech support in California said they haven't heard anything about this, but it has been a plague. I hope this helps.