Google ical calendar not updating
Adding a query parameter (or attempting to add another one) will cause Google to treat the calendar as a new feed.
Here's an example with the UK holidays calendar feed from Calendar Labs: Original Calendar URL: etc.
Although Google updates the calendar automatically from the Timetastic feed the timescales for this are somewhat unclear and there is no manual way to force the update.
Some observers have suggested Google updates every few hours, but Google themselves quote it may take up to 12 hours, although in in exceptional cases we have seen it take as long as 48 hours.
I wish we could provide something more concrete on this subject, but without any further specifics from Google or guidance from them on how to force a refresh, it's just a matter of time.
Android Important: These steps may cause you to lose some unsynced data.
Any event information you can't see on Google Calendar on your computer will be lost. When you have an app open and tap the Home button, the app is closed but it doesn't actually quit.