I doubt if this is related to SVG 2.0. It appears to be a scaling issue of some sort. There is an ellipse in this drawing with a very wide stroke and a black fill. If I edit the stroke width and remove the fill I get the attached result. In Inkscape this result looks more interesting, however, the IE11 display is still incompatible with Inkscape so there may be some other problems as well.
I doubt if this is related to SVG 2.0. It appears to be a scaling issue of some sort. There is an ellipse in this drawing with a very wide stroke and a black fill. If I edit the stroke width and remove the fill I get the attached result. In Inkscape this result looks more interesting, however, the IE11 display is still incompatible with Inkscape so there may be some other problems as well.