General Split screen on iPad Pro 12.9 / Facebook wont do split screen?

[Synergie]

I can’t get Facebook and messenger to do split screen side by side. I can only get messenger floating. Do only some apps work in split screen?

 

[chabig]

Apps have to be coded to work in split screen. Some developers are either lazy or they've made a bad business decision not to share screen space with others.