This occurred to me as well. Turns out I had one party engaged in combat off screen, and it wouldn't advance the turn until I watched the little auto-combat animation play, and it wouldn't play until I had the chars on screen. Click through all your army icons until you find the one that's killing somebody, once you see the animation play out, you should be able to advance to the next turn.
An alternate solution is scrolling way out and you will be able to "see" the unit do it's animation. I actually have a different issue causing the turn not to advance. One of my stacks ran into a spider pile and couldn't figure out how to go around. I can split all but one of the units out of that group and move them, but the one unit that was leading the group can't move. I saved and called it a night I will see what happens tomorrow. I can go back to an autosave if it doesn't fix itself.
