I have recently updated my Phone Software & PC Suite , All the anniversary date in my calendar are removed .
Previously I was able to see them in Calendar . Now in calendar those dates are not there. They are still there in NOKIA PC Suite application.
I have NOKIA Asha 202 below are its configuration .
PC Suite: 3.7.22
Previous Phone Software Version : 20.48 (Not sure exactly)
You may give this a try.
If you have some calender events on your pc suite then try to synchronise them with microsoft outlook on your pc first.
Click on syncronization on PC suite main app and select outlook(You need to open outlook before this and set it up for use).
After syncing calendar, contacts etc, open Nokia suite, select sync-sync now-calendar and tasks.
Now check whether they are synced to your phone or not.
Hope this helps.