Unable to set value of actor reference in blueprint defaults

When an actor reference is added to a blueprint, the value of the variable cannot be set in the blueprints details panel.

For a code based reference variable, the dropdown to set the value is available but the box will continue to show "None" regardless what is set in the dropdown.

1. Open UE4 Editor
2. Add Blueprint based on Actor
3. Click green Add New button and choose Variable
4. Set variable type to Actor->Reference
5. Compile Blueprint

Result:
The default value for the variable cannot be set inside the blueprint.

Expected:
Variable can be set to any valid reference after being created.