I am having an issue when rendering out a video through Matinee. For some reason there is a random sphere object that appears at the world center axis, but only when rendering a video. It does not appear in the editor window, nor does it show up in the Matinee video.
This sphere represents the player and will appear wherever the player is when the matinee is triggered. You can hide the player in the cinematic by ticking “Hide Actor” in the details panel of the Matinee actor.