Cannot mirror print in landscape

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I need to create a PDF of slides to be viewed through a mirror (on a Teleprompter). The Postscript printing option Mirrored Output does this, but it appears to ignore the page orientation settings. They always come out portrait even though everything is set to landscape. I have also tried Auto portrait/landscape, but the output is the same. Is there a workaround for this? It appears to be broken. (This is on Windows 10 using Acrobat Pro DC 2015.023.)