I have the same issue, upgraded to 14.2 from 14.0 and clients to 14.2.335.1000, and were now showing over 800 machines of 1700 that are reporting that the IPS definitions are out of date (virus defs are correctly updating however).
Updating a machines IPS definitions manually works, but obviously its not practical to update all in this way. No other changes have been made in the environment.