If you add a scene to the Build Settings list and then change the name of the folder that contains the scene, the next time you boot up Unity the references to those scenes will be lost in Build Settings. They will appear as "deleted".

1. Boot Unity and Create a new project using any template
2. Open the Build Settings. Confirm that the SampleScene has been added to the scene list
3. Rename the folder containing SampleScene
4. Save the project and close Unity
5. Boot Unity
6. Open Build Settings
7. Reference to SampleScene has been lost

Occurs on 2018.2.0a8, 2018.1.0b13, 2018.1.0b5, 2018.1.0b1, 2018.1.0a7, 2018.1.0a5

Does not occur on 2017.3.1, 2018.1.0a1, 2018.1.0a4