Splitting out from T97901 -- the non-SVG mode for images in popups doesn't work in IE 11:
"I notice that Chrome is getting an SVG embedded image (wtf?) with explicit width and height set while IE 11 and Spartan/Edge get a div with a style="background-image: url(...)" *and no height set*.
The lack of a height means the div, unlike the svg, gets 0 height and the image is thus invisible."