Rendered single image perfect but rendered animation has object dissappearing

I have finished a 650 frame animation. When I render a single image as PNG image the render is perfect. However when I render the whole animation as PNG sequence, the images making up the section where I am employing a Child Of constraint has the problems of the object (Hat) under the influence of Child Of constraint disappearing from the screen. However the following section of the sequence when the Child Of constraint has no more influence the images render perfect with object (Hat) back in scene.

First image is image 90 from the rendered sequence. Second image is image 90 rendered as a single image (Hat is present).
Could this be a problem with the latest Blender 2.81a version?
What could be causing this problem and how to fix it?