The rollback was performed because the timer for thralls was set to one day. In your case probably a new problem was raised, because the remaining vacation timer and thrall decay timer are not the same. You will probably not be the only case.

In addition to the clear picture.
The thralls have no timer like bases, where it runs individually, but are based on the last login. So in case of a change not the old one is valid, but directly the new one.