Sparklemotion have you installed the kepub Output Plugin in Calibre ?
https://www.mobileread.com/forums/sho...d.php?t=220565
I have that and when i send my epubs to my Kobo devices they appear as Kobo Epubs which I have been told are Kepubs. That might help the display.
I must admit I like the ReadScreen=True option but it has an intermitant bug in that the last letter of a row is cut off so I tend to show headers and trailers now.