I have schedule event that I've been having issues with. A couple of days ago I added code to log when it was being run and left it. It was scheduled to run every hour and the log was logging it has running every 2 hours, so I just set it to run every 30 minutes and I now find that it isn't running in the even hours. Here are the last 5 rows of the logging table and the time now is 12:43, so there should be 2 rows for 12:07 and 12:37.

2015-07-17 11:37:24
2015-07-17 11:07:24
2015-07-17 09:07:24
2015-07-17 07:07:24
2015-07-17 05:07:24

Any ideas why his might be happening and how to fix?