When a character gets both an extra attack and an extra turn at the same time, the extra attack is taken and the extra turn is not given.
EDIT: Hmmm. That's not exactly it. I think it depends on which is awarded first, the extra attack or the extra turn. And it only glitches when there is a single extra turn given. I need to pay closer attention to this as I am a little confused. Too many icons flashing during battle!
And just now I cast the Soulmancer's Freeze spell on the enemies and one of them who was already frozen and still has the frozen ice below him, no longer has the ice on him. So I am guessing that he was affected, but in freezing a frozen enemy, the ice was removed, visually only.