Using a Directional Light, Sky Atmosphere and SkyLight. When lighting the scene with Lumen you can see the sun disc and get a bloom/glare from it. In Path Tracer the sun goes invisible and no bloom is created from the sun, only the sky.
r.PathTracing.VisibleLights 1 fixed it. I thought documentation said this wasnt needed for directional lights but using it allows the sun to be visible