Symptoms
Not seeing all the audit history records when using the Calendar view
Resolution
There is a maximum of 250 audits for the calendar view. When viewing the calendar view, you will notice the 'Update count' label (at the top of the page) is maxed out at 250 audits.
You can increase the glide.history.max_enteries property. It can have the potential to increase the loading of the calendar history page. Also keep in mind that it will still only show the entries from oldest to recent, so if you have 800 audit records and you increase the property to 500, you still will not see the most recent 300 records.