IK bones stuck in first frame of animation while it plays.

My IK bones (bones parented to the root, that are constrained to hands and feet during animation so that they can be used as IK targets for the limbs in game) stay put in the first frame of each animation they blend in to. In UDK translation was disabled by default and there was a tick box to enable it in an animation. However, I have not seen this in U4 and so I am unsure what the problem is.