Wireframe box does not appear when adding blueprint of custom volume class to the viewport

No volume appears when adding a blueprint of a custom volume class to the viewport. Adding an instance of the custom class directly does show the box, but additional functionality cannot be added via the blueprint.

1. Open UE4 Editor (any project)
2. Create a class based on Volume (MyVolume)
3. Change UCLASS() macro to UCLASS(Blueprintable)
4. Compile
5. In the editor, create a blueprint of MyVolume (MyVolBP)
6. Add instance of MyVolume and MyVolBP to the viewport

Result:
MyVolume shows the wireframe volume box when added but MyVolBP does not

Expected:
Volume Box of custom volume class blueprints appear when added to viewport

Impossible to create blueprint from custom c++ class derived from volume