I imported an asset from the construction bundle and manually added 2 spotlights. As you can see in the 1st image (Unreal Editor), the lights are 100% visible.
@AMe3e Thank you for your report! We would like to look into this further, would you be able to submit a bug report using the form available here? Fortnite Creative
The problem was that the spotlight was too deep inside the prop. Pushing it forward fixed it. However, it was weird that the spotlight could be seen in the editor.