I've not used Litchi, but I'm guessing the distance readout at the bottom left of the screen is distance from the "home" point or launch point, rather than distance from orbit target. If you're standing a few meters away from your launch spot and do an orbit around you, rather than the launch point your distance readout will increase/decrease as the drone completes the full circle around you.
Try launching then standing exactly on the launch point and do an orbit and see if the distance readout stays the same.