live camera and Iphone tracking version tag (4-27)

a quick question for UE4.
For a 5 minute lecture, i wanted to record live-footage thats keyed in my own created map.
But I also wanted to pan the camera with my iphone as a tracker.

Version 4.27 Here is my problem, when i am recording in UE4 and press play to start my live camera it does not appear.
I can move the virtual camera with my iphone but the plane on which the footage should be is just black.

The Camera is blueprinted so that when i press start- the camera starts. I can also see it working just in the recording its black or a freeze frame. Any help?

Set the project settings (?) pixel format to be 8bit instead of the default 10bit. Search for format in settings.