Cortana, Third Party Calendars Show Double Events, Deleted Entries

I use Hope Calendar and it shows entries I have deleted from Mail and Calendar. So does Cortana. This clogs up my calendar, obviously, and also leads to duplicates (screenshots included). Clearly when I delete an entry from Mail and Calendar it isn't really gone. Does anyone know of a way to flush/reset the sync, so that Cortana and third party calendars work properly? (Note, second image borrowed from another thread, figured no one would mind.)

Untitled.png

12555.jpg

Attached Images

• Untitled.png (18.7 KB)
• 12555.jpg (22.2 KB)

from Windows Central Forums http://ift.tt/2uyxFaB
via IFTTT