Win. MR & HMD shows SBS 3D as 2D SBS. How to display as 3D?

[Donald1800]

I have Win. Mixed Reality with Odyssey+ HMD - works great in 'Portal'. Attempted to view/play an archived SBS 3D movie, both in a system 'Video' folder and directly from a USB 3.0 thumbdrive using the menu icon "Movie and TV". 'Portal' is properly displayed in 3D, but the movie is displayed in 2D SBS, just as it would be displayed from my laptop monitor. I could not find any menu option that allows 3D display setup. How can I watch 3D SBS with my setup?