Incomplete Calendar search results

When I search for periodic events in my calendar I get incomplete and incorrect results. This seems to affect events that I have modified after original input.

I've just searched for a series of 10 appointments. I'm getting 8 results. Of those results, I had previously had to change the date of about half of the original appointments, but in search results they are showing up with the original date (from when I first input the series and before I made any changes).

In addition the search result doesn't show the first two events which are in the past. However if I modify those two appointments by for example adding one new character, this causes it to show up in search.

A final point. If I conduct the same search in Spotlight I get 10 correct results. The problem only exists inside calendar, no problem in Spotlight

Alu Macbook late 2008 running 10.1 El Capitan - Calendar Version 8.0 (2092.3)