IE11 and older doesn't support HTML5 drag and drop for SVG elements. I made a simple Codepen that you can use to test on different browsers.
You'll need to do manual hit testing if you want to support drag and drop on SVG elements. If you're interested, you can take a look at drag-drop.dart. It's a library of mine that supports cross-browser drag and drop on SVG. Documentation is non-existant, but you can look at the examples and tests to get an idea of how to use it.