I am not sure what I will talk. But I imagine that another reason to the constant crashes would be the declaration of UPROPERTY.
private:
UPROPERTY(VisibleAnywhere)
USceneComponent* Root;
UPROPERTY(EditAnywhere)
UWidgetComponent* PaintingGrid;
UPROPERTY(EditAnywhere)
UWidgetComponent* ActionBar;
I am not sure, but I believe to change the UPROPERTY from VisibleAnywhere to EditAnywhere, despite being heavier, would be better to access and modify it.