I am new to this game but not to turn based strategy and RPG type games. I played through the tutorial and then set up a game of my own (not a scenario). I am really enjoying the game, but I have found that my sovereign that I started the game with cannot gain any experience now that he has hit level 8. When I win battles i see my units and other heroes that I have recruited via my 'fame' gaining XP but my sovereign always shows '+ 0XP'. I searched the whole user manual for some kind of clue as to why this is happening and could not find an explanation. Can anyone point me in the right direction as to why this might be happening?

Thanks in advance for any help!