This guide explains the various ways to troubleshoot your subscription calendar.
Events from the subscription calendar are not showing on my Apple device (subscribed using Google Calendar).
- This is typically for users who have subscribed to a calendar using Apple (desktop) or Windows (desktop) and is using Google Calendar.
Events from the subscription calendar are not showing in the Google calendar app (Other Calendar services too like Outlook, Apple, Yahoo, etc.)
- Make sure that the subscription calendar is checked on the user's Other calendars section. If the calendar is unchecked in the list, they should check it. If it does have a check then they need to re-subscribe again to the calendar since every new subscription creates a new calendar URL.
Google calendar screenshot from a desktop

Google calendar screenshot from Android after clicking the toggle menu on the top left part of the page

I’ve added new events but subscribers can't see them on their calendar
- When your users follow your subscription calendar, a unique URL for your calendar is stored in the user's calendar client (Google Calendar, Outlook, Exchange, Apple Calendar, etc). That unique URL is regularly requested by that calendar client to sync with your subscription calendar. When this happens, any changes you have made to your subscription calendar are synced with your followers' calendars, so their calendars stay up-to-date! The frequency of this request/sync depends entirely upon the calendar client.
- Apple updates upon app / program startup & every 1-3 hours
- Google normally updates every 24 hours.
- Outlook updates upon app / program startup & every 1-3 hours
- Outlook.com updates every 3 hours
- Yahoo updates every 8-12 hours
- Another thing that users need to check is if Out of Office is set up on their calendar. If the event over lapses the date they are out of office then it will not be shown. It automatically declines new events (but also has an option to decline existing events depending on the user)
The subscription calendar is not being synced with the iPhone apple calendar app because apple does not sync subscription calendars between mobile and desktop/iCloud
- The users need to subscribe separately on both devices
I subscribed using my iPhone Google calendar but it's not being synced with my iPad's Google calendar app
- To sync the calendars across your devices, make sure you’re signed into the iCloud with the same Apple ID on both your iPhone and iPad.
- Open the Settings app
- Tap your name at the top and choose iCloud. If you use iOs 10.2 or earlier, tap Settings > iCloud
- Enable the Calendars toggle. Make sure it's enabled on both iPhone and iPad you want to sync

Calendar no longer syncing after a big time from the last sync (48 hours +)
- Make sure that the subscription calendar is checked on the user's Other calendars section. If the calendar is unchecked in the list, they should check it. If it does have a check then they need to re-subscribe again to the calendar since every new subscription creates a new calendar URL.