Can't save image on iPhone in any format

Hi - I upgraded to premium so I could get a high res image. I was able to create and visualize it all on my iPhone, but when I tap a PNG file it opens a new, blank, "data" browser window. I have tried Chrome, Safari, and Opera. Help?

HiRes PNG images don't work on iPhone and some old iPads because of limitations in the devices. Please find a PC or laptop and save HiRes PNG there.

BTW EPS and SVG export should work fine on both iPhone and iPad.