Question Can't render UI on Oculus 180/360 video example

Hello everyone, I've been playing with the Oculus 180/360 video example included in the Oculus Integration package. The demo scene is called "Stereo180Video" if you want to take look.
Now I need to render some UI elements, and they need to be placed in "world space" mode. But even when they are visible in the scene, they are not visible to the camera (they actually disappear from the screen when the video is loaded/playing). However, the UI elements appears if I change the mode to "Screen Space" modes (check attachments for further reference).

Any idea?