The reason you are only seeing 400 contacts listed when you click on the list is due to a setting we have that only shows 400 of the contacts you have on the list. We are working on having it resolved as soon as possible but all of your contacts on are that list.
To view all that contacts you have on your list, please click on another list of yours and then select add contacts. From there select your list . You will be able to see all of your contacts listed in your list .