I have found that if one sets up an event eg on mouse clicked on the base of a template and then exits the designer if you then re-enter the designer and look at the event then this event has not been saved - although it will still have been working on the deployed objects. If the event is set up on say a container within the template then all works OK
There was indeed a bug with events on the actual template base not being saved. This has been fixed for 7.4.2