try this in the header
UFUNCTION(BlueprintCallable, BlueprintNativeEvent, Category = "Combat Hex Grid")
void CreateGrid(UDataTable* DataTable, UPARAM(ref) const TArray<ABasePartyCharacter*> &CharacterList);
const is optional but it’s more optimized if the compiler knows that characters won’t be changed in the function
in cpp
void ACombatHexGrid::CreateGrid_Implementation(UDataTable* DataTable, UPARAM(ref) const TArray<ABasePartyCharacter*> &CharacterList)
{
}
That way you get this in bp
And the override