I am near the end of the 41 campaign and I have noticed that my core units are maxing out at level 13 with stars ALMOST filled in to 14 - but they never get there. Is this a bug? Has anyone else seen this? If I have to reload the game and all the campaigns how do I save my games - I can't find the save file.
Not a bug, but by design. The DLC's have experience caps that gradually increase as you progress. As far as saves go, those are located in Documents/My Games/Panzer Corps/Save. You really can't do much with them, though, since they are generated in game. However, you can back them up if you ever need to reinstall windows or the game.