Unable to save project due to user created blueprint node that creates user created object

When a user creates a blueprint node of their own that is used to spawn a user created object, the project becomes unable to be saved after the blueprint is put into use.

1. Make a new project with Unreal Editor 4.7.6 of the C++ type, basic code, with starter content (Name it MyProject8 to bypass step 3 and any need to edit the .cpp and .h files attached, if possible)

2. Add the attached code files to the source folder (MyDocuments/Unreal Projects/ProjectName/Source/ProjectName)

3. Open the .cpp and .h files to make any replacements to the #include statements due to a mismatching project name (Comments included)

4. Return to the editor and create a new blueprint of the class Actor and place it in the scene

5. Open the blueprint in the blueprint editor and navigate to the Construction Script tab

6. Drag the exec pin from the Construction Script node and release to search and create a 'Create Flower Object' node

7. Right-click the Return Value pin on the Create Flower Object node and select 'Promote to variable'.

8. Compile and save the blueprint

9. Select File > Save All

10. Notice that you are unable to save and given an error message.

GameState returns null?

GameState returns null?

Can't save due to "Graph is linked to external private object"