Maps fail to respond to any changes made in the CDO if any value has been modified in a loaded instance

TMaps do not function as I would expect when blueprinted. Any change made to the instance completely disables inheritance of all changes to the CDO, rather than only overriding the keys that are modified.

Repro as pictures follows.

Initial situation:
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Modify Foo in instance:
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Modify Bar in BP:
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Add Baz to BP:
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Definition of test class used:

UCLASS(Blueprintable)
class AMapTestActor : public AActor
{  
GENERATED_BODY()  

public:  
UPROPERTY(EditAnywhere, BlueprintReadWrite, Category=Test)  
TMap<FString, int> Map;  
};

1. Create a Blueprintable actor class with any map as a UPROPERTY, eg. TMap<FString, int>.
2. Create a blueprint class from the class.
3. Edit the blueprint, and add 2 keys, eg. "Foo" = 100, "Bar" = 200, save the blueprint
4. Create an actor from the blueprint.
5. Observe that all changes made in the CDO are reflected in the instance.
6. Change the value of "Foo" to 101 in the instance, save the instance
7. Change the value of "Bar" to 202 in the CDO. Compile.
8. Observe that the change to "Bar" is not changed in the instance anymore.
9. Add a third key, "Baz" = 300 to the CDO. Compile.
10. Observe that no "Baz" is added to the instance, this is a bug
11. If you save the CDO (but not the instance) and reload, it will actually apply the changes. But if you saved the instance in a broken state it may stay broken