Hi Mike, do you have more than 40 installed? From Max's documentation here http://moi3d.com/forum/lmessages.php?webtag=MOI&msg=6507.1 :


ExtScripts
--------------
This addon dynamically generates list of all external scripts. Also it adds to the list some "hidden" MoI commands.
There is another version of this addon - ExtScriptsFull. It works exactly as ExtScripts, but It loads all MoI commands.
You can open ExtScripts.menu.htm(ExtScriptsFull.menu.htm) with Notepad and edit "maxlines" value ( default 40 ) to change the maximum number of lines.
By default this addon checks only /commands directory, but you can create /customui/mods/ExtScripts.cfg.htm with notepad to add any directory you want.
Example:
MOI\commands
MOI\commands\myscripts
MOI\myscripts2
D:\dir1\dir2\myscripts3

Note: As you noticed (or maybe not), I always use "_" symbol in the beginning of my scripts names. Using this trick I can easily find and manage external scripts in /command directory.
ExtScripts automatically removes "_" symbol, so "_vClone" script will be shown as "vClone".