I'm getting buggy behavior with clipPath transforms in Edge also. Specifically trying to use scale on a polygon clipPath, Edge can't seem to render the animation - the end position will suddenly appear if you click the SVG canvas. It doesn't seem to be exclusive to polygon, though, as I had the same experience with rectangle (rectangle actually gave me similarly buggy behavior in Chrome also). X and Y position transforms seem to work fine.
All and all, support for transforming clipPath seems to be pretty crappy at the moment.
UPDATE: Figured out the issue, see comment below.