Why is my Windows phone running on 8.1 deleting calendar entries more than three weeks old?

[Windows Central Question]

My HTC Windows Phone running on 8.1 has suddenly deleted calendar entries more than three weeks old, although the entries are still there at Outlook.com, and in my tablet app. The only historical entries left are the ones which repeat into the future. Closing down the phone and starting it again has not triggered any syncing restoring process. Email syncing is working fine. Any suggestions on how to solve this please? DL, London UK.

 

[xandros9]

I think there may be a setting that controls that but I don't recall for sure where it is. I would poke around the calendar account settings and see if there is a setting for how long in the past to sync events.