Steps to reproduce the outline issue:
- Create a project.
- Open the project settings, then make the following changes:
- Rendering > Default Settings > Anti-Aliasing Method: MSAA
- Forward Renderer > Forward Shading: Checked
- In the level, do the following:
- Remove the sky sphere and the atmospheric fog.
- Insert a SkyAtmosphere object.
- Insert a cube or some other mesh.
- Move the viewpoint so that the mesh obstructs the sun (doesn't matter if you're in PIE or not). You should see a black outline around the mesh.