SCCM has a default limit of 2000 items that it displays, if the number of items in your Add/Remove programs is more then you will not be able to see them unless you specify a higher value limit.

You can do this by adding a new Dword called ValueLimit under:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\ConfigMgr\AdminUI\QueryProcessors

and entering a higher number as a limit. [Link]