There have been a few reports about a bug where you kill a monster and the character that killed it gets their speed reduced permanently. Fromahead knows this and have released a new update with its fix. All that's left is to wait for Apple to approve it.
EDIT. I had just gotten another report where you lose 1 character level when your party gets wiped out. If you have experienced a similar bug, please contact me by emailing email@example.com . P.S. A good way to avoid this is by pressing the leavemission button right before you're about to die. (you keep the exp crystals you have gained throughout the mission)