To expand upon what AmphDev said, I would only make the property BlueprintReadWrite if you have a need to edit the array in blueprints. Otherwise I would recommend keeping it as BlueprintReadOnly and VisibleAnywhere. In this example the Uproperty shouldn’t have any effect on your code however, I’m almost certain it’s the missing type , like AmphDev pointed out.
My blueprints code will only read the information, just C++ code will write it in the array.
I know I can just code it to not write in BP, but do I really need to ever have this “ReadWrite” property? Tought it was meant just for BP, and wouldn’t block the C++ add. I am wrong?