To receive updated data for synchronized calendars and calendar subscriptions regularly please check that your iOS System Settings are correct.
- Select device Settings
- Since the location of this setting changes often in the iOS Settings app, we recommend searching for the word "Fetch" in the search field at the top of the settings page. Tap "Fetch new data" in the search results.
- This brings you to the Accounts section, where you will see a list of your linked accounts.
- Select Fetch New Data below the Accounts list.
- Set it to Push for regular accounts (then they will be refreshed automatically) and
set all Calendar Subscriptions to Fetch Every 15 Minutes.