I have a custom timer job with a yearly schedule (
SPYearlySchedule). After I deploy it, its Schedule Type listed under Job Definitions in Central Admin is shown as Yearly as expected. However, if I manually run this timer job (by clicking "Run Now"), the Schedule Type for the job is immediately changed to Hourly - and indeed the job will run every hour after this, instead of every year.
Note that this problem doesn't occur if I use other schedule types such as
SPMonthlySchedule, i.e. schedule types for which SharePoint actually has UI for (SharePoint's UI lacks a radio button for a yearly schedule) - so this is not a problem related to my source code.
What could be the cause of this? Is this yet another SharePoint bug?