I figured out what the issue was:
It's on Hyperbian side, where I have a usb camera grabber with lower priority for when watching native TV content.
I set the "trapezoid" percentages (in led configuration) to match where the webcam sees my screen.
This was reflected to the image captured by the android app and hence ignoring the screen edges.
Setting all leds to 0%/100% as they were by default fixed it.
Is there some way to use different led percentages for different grabbing sources?
Thank you