can't save project

I’m a novice/learning UE4, but a long time C++ programmer. I’m playing with the Stick Figure 2D demo and I added a test Pawn C++ class. It was fine until apparently something I did caused this:

Can’t save …/…/…/…/…/…/Unreal Projects/UnrealStickFigure2D 4.10/Content/Maps/TrainingMap_1.umap: Graph is linked to private object(s) in an external package.
External Object(s):


The asset ‘/Game/Maps/TrainingMap_1’ (TrainingMap_1.umap) cannot be saved as the package is locked because you are in play on PC mode.

Cancel: Stop saving all assets and return to the editor.
Retry: Attempt to save the asset again.
Continue: Skip saving this asset only.

I can’t save the project because of this. I’ve set the “Play” button on the Editor become Standalone because I was tired of Editor crashes, and I’m wary of changing it back to run in the Editor.

But does anyone have an idea how I’m supposed to find this mysterious private object, which seems to be “AssetImportData”? I can’t find this anywhere in the Editor and I don’t have a reference to it in my C++ code.

Sounds like you just have to stop/exit “play on PC” mode (close the standalone window), have you tried that already?