Hi there, here is a link to a fix for the provisional leaders...
http://forum.paradoxplaza.com/forum/showthread.php?611226-Leader-System-Fixes&p=13909729#post13909729
This file should apply to even an existing game, and should not require a scenario rebuild. Enjoy!
It should fix...
#1. Starting leaders for all nations that have leaders.
#2. Changing leader pools for the major nations (now your leader pools should grow as your army does).