In Augmented Reality (AR), what causes a virtual object to appear 'stuck' to the screen rather than properly residing in real space?

Answer

The virtual object’s shift does not match the real shift as the user moves the device.

For AR to be convincing, the virtual object must react to the user's movement exactly as a real object would. A failure in matching the parallax shift creates an inconsistency the brain detects immediately.

In Augmented Reality (AR), what causes a virtual object to appear 'stuck' to the screen rather than properly residing in real space?
physicsastronomyopticsparallax