Siri keeps deleting future events in my calendar

After certain iPhone apps add new calendar entries for upcoming events, a few days later I get a Siri found events notification that is trying to delete those same events! Very annoying! Siri takes my calendar entry that was already previously created and puts a strikethrough in the title and my only option is to ignore Siri or delete the event to remove the notification. Why is Siri finding future events in my calendar and deleting them!?