I set Responsive Playback to "Landscape" and yet the slide shows up in "Portrait" until I rotate my phone.

I set Responsive Playback in mobile to "Landscape" and yet the slide shows up in "Portrait." I published to Review 360 and sent the link to my own email. I click on the link in the email and it shows up in vertical mode. I can rotate the phone and get it horizontal, but I don't want the option for vertical (hence setting to landscape). It's too small to be viewed vertical and wastes space at the top and bottom of the screen. Users may not know to turn their phones, so I need to going horizontal by default. As of now, it appears setting landscape only does nothing.

Am I doing something wrong/missing something?