Default Immersive mode for games stock

Hi all,

can anyone tell me why Immersive mode doesn't work for certain games like NightSky and Kingdom Rush?
They seem to start in full-fullscreen (1080x1920) and the the navbar appears on top of the screen and cuts off the right edge.
Is this related to the forced landscape mode in those games? (It worked for the game SimpleRockets for me, which uses portrait in the menu)
I tried it by using the Xposed module Immerse Me, which did work for normal apps, but as said some games didn't.

Best regards,
Philipp