If you getting that error only in Error List then just ignore it, that file needs to be generated first so after compile this should disappear… even if not and if still works it’s ok. You should only consider errors during compilation as IntelliSense have problem understanding tricks used in UE4 and create false errors.
As for value contain enums in C++ it a feature of co called enum classes
https://en.cppreference.com/w/cpp/language/enum
UE4 reflection system only supports uint8 enums, so you can do this:
UENUM(BlueprintType)
enum class GroundDirection : uint8 {
DOWN = 0 UMETA(DisplayName = "DOWN"),
LEFT = 1 UMETA(DisplayName = "LEFT"),
UP = 2 UMETA(DisplayName = "UP"),
RIGHT = 3
}
You don’t need to type i values either, compiler will automatically use numbers from 0