Just to confirm, when you say SVG do you mean Scalable Vector Graphics? I can't say I've come across the request before so I'm not sure at this juncture whether or not it's supported. Additionally can you provide your application build number since we would need that to confirm if it's supported in your build.
Update: Confirmed from Campaign R&D that SVG images are not supported at this time. An enhancement will be submitted to support these images in the future. Till that time, changing the file extension is the correct workaround.