I have the same issue. I have lots of pictures that are SBS vertically stretched, like this one: https://bipedu.files.wordpress.com/2012/10/hsbs.jpeg
The app renders the 3D effect correctly, but the final picture has only half the width (or double the height) as it should have.
It would be nice to have a toggle in DeoVR to double the width of a SBS picture or video, because this format is quite common.
Can you please clarify if there is currently any workaround?