Are you in the back airbus320? We were told that they do not assign seats on LH in economy for "security reasons" I know this because at first LH couldn't confirm us in J for the inter Europe flight yet they would not give us a seat assignment in Y. We eventually got a flight in J and they would confirm us there. I guess "those type people" aren't really a threat

Wait till you try to board a LH flight. Even an F seat going transatlantic doesn't get you priority boarding.