My moral usually hangs around 75. Party morale is high enough that I'm getting a speed bonus from it. Never gotten a single point of XP, let alone a skill point.
Interesting, but none of those things you mentioned applied to my situation. No companions were sent on other missions. This was also the first time I attempted this mission, so no other "borrowed troops" leftover from any other instances. Next time I attempt this mission, I will try what you suggest about removing the un-upgraded borrowed troops.