[4.7.6]"Graph is linked to private object(s) in an external package."

[rit]

1. Create a BP class derived from CanvasRenderTarget2D (BP_scriptedTexture)
2. Create a BP class for a staticmesh (BP_Console)
3. In the construction script of BP_Console, Create CanvasRenderTarget2D, and set class to BP_scriptedTexure
4. drag BP_Console to map
5. this warning pop up every time I save or auto save:

Can’t save …/…/…/…/…/…/Unreal Projects/CGame3D/Content/StarterContent/Maps/Minimal_Default.umap: Graph is linked to private object(s) in an external package.
External Object(s):
BP_scriptedTexture_C_7
/Engine/Transient

Try to find the chain of references to that object (may take some time)?

Please Help.

Here is the reference graph of BP_Console:

[anonymous_user_59012487]

This is still happening, took me a long time to find the class that I had in my player which was derived from CanvasRenderTarget2D and remove it.