The lens flare element is using a fill option within shape>style tabs of the inspector.
It has been set to work with the media drop zone within the template which is set to see through its fill layer.
The way I quickly fixed the problem was to uncheck the fill box and tick the outline box.
Then set the brush opacity to 0% and the width to whatever but not 0.
Seems to have worked. If I knew more I’d look around within the blending settings of the layers.