Symptoms
- None of the UI elements are showing in the scene view.
Cause
- The UI layer is hidden.
Resolution
- If the UI Layer is hidden, un-hide it. To do so just click on the Layers dropdown to the upper right of Unity's Editor and click on the layer you wish to un-hide.
More Information
- http://docs.unity3d.com/Manual/Layers.html
- In now deprecated versions, there was a bug that could cause invisible UI elements. In this case, the solution is to upgrade to unity 5.3 or higher
- http://issuetracker.unity3d.com/issues/sceneview-ui-no-longer-renders-in-the-scene-view