Trouble with "Recurrence" on iCloud for Windows

I just installed iCloud for Windows on my PC. My Calendar now won't accept a recurrence properly. It does it right if I am trying to set it for a specific date each year, e.g. someone's birthday on April 23rd each year. But it won't set a recurrence for Mothers' Day which is the second Sunday in May each year. It sets it according to the date I start the series. When I set it up beginning this year it is on May 8. It then sets it on May 8 every year.