When the combat ends, the "slow motion" doesn't stop until the "continue" window appears.
So, that means you will wait 20 or 30 seconds for the animation to stop itself.
It happened to me several times, and i think (but i'm not sure) only in the Underworld Mode.
Here is a screenshot of the team i had on the last two fights (where the bug occured, and not before).
I hope it will be useful