I out of synced from a battle with an elf (myself playing as orc).
After that I had double the amount of ogres and catapults I should have had, but was missing a few other units I did not lose in the fight, including my hero.
The normal relog and restart later, he is still missing.
I could very well live with the loss of a few units, but the hero being gone is quite an annoyance (regarding the whole "You need your hero in the army to acess quest areas." thingy)
The related log should be this one, although I'm not really sure as I noticed the missing hero a while later when I wanted to continue questing.