You need to wait until the MAC number changes into a name or IP address. If you give your devices names, then eventually you will see their names shown.
I guess it has to do with how recently the devices have been linked to the specific AE.
Could be related to how device names are shown in local network protocols (in Win speak it used to be in Netbui). No matter what I do, my Epson Printer still shows up as EPSON3709F but my HP8100 is correctly displayed as Twig. Do your OSX devices show up properly ?