I had the same issue with characters getting stuck during combat that was mentioned by Damashi. In one battle I had two characters get stuck, leaving me with only two to use in the rest of the battle. The stuck characters won't move and there toolbar is greyed out, this continued after the battle was finished. I found a work around the first time it happened Loshe and the Red Prince were stuck, after the battle (which I was lucky to win) I traded a ring to the stuck character and equipped it, this did mange to unstick them. The next time it happened it was Sebille, I sent her the ring during the combat session and equipped it successfully returning her to the battle.
