Hi there I am also having the same problem. But mine is more extreme. ALL my non-recurring events are missing! My recurring events like birthday is still in my iphone. I am syncing from my outlook and all the appts in my outlook is intact but they are not able to be seen on my iphone except my recurring events.
Not only my iphone 4 but my ipad too! I have ensure the settings on my iphone 4 shows "calendar from my PC" only and yet I cant see any non-recurring events.
Lastly, I cant delete a recurring event on iphone 4 no matter how many times I tried to delete it. But strangely I can delete that recurring event on the outlook but after syncing that event still remains in my iphone 4.
I have tried to reset, reinstall and backup or a new phone but to no avail!