I played around with adding animated svg's, sozi-presentations, in Mendix, but failed to get it running too. Maybe you can replace the svg with css or js content and make that animate using one of these two widgets from the appstore:
- https://appstore.home.mendix.com/link/app/111890/
- https://appstore.home.mendix.com/link/app/110956/
I also came across this issue recently but I now prefer using this SVG Animation tool to create interactive SVG animations