This problem appears to have started on 11/02/2015. The actions themselves appear to work just fine (for instance if you set the action to display in the survey you’ll see the response), but the action log is not displaying the response from the action.
Stay tuned for updates on this one!
This is now resolved by our Engineers! This will not bring back any previous data in the action log, but it will work going forward.
Let us know if you are still seeing issues!