AllowedClasses - Picker is empty

I’m not sure what you mean by creating a blueprint from the struct? I created a new class (MyActor) and added a struct:

USTRUCT(BlueprintType)
struct FMyStruct
{
	GENERATED_USTRUCT_BODY()

	UPROPERTY(EditDefaultsOnly, Category = Test, meta = (AllowedClasses = "MyAssetClass", ExactClass = false))
		FStringAssetReference MyStructAsset;
};

After compiling I created a blueprint of MyActor and was able to add a variable of MyStruct. After compiling the blueprint I could select the My Struct Asset drop down which showed all available actors/classes.

Can you elaborate on your setup or what I’m doing differently.