Since you're experiencing issues specifically on your iOS devices, I'd give the following steps a try and see if any of them resolve the issue.
- If recent changes simply don't appear in Calendar, try forcing a refresh by tapping Calendars in the top-left corner of Calendar to load the Calendars list. Then, tap the Refresh button in the lower-left corner of the Calendars list window.
- Quit and restart the Calendar app on your iOS device:
- Press the Home button.
- Double-press the Home button to open the multitasking menu.
- Tap and hold the Calendar icon until it jiggles.
- Tap the "X" to remove it from the list.
- Press the Home button to get back to your Home screen. Wait a minute before reopening the Calendar app.
- Restart your iOS device by holding down the Sleep/Wake button and then swiping the screen when prompted to Turn Off. This may sound simple, but it does reinitialize your network and application settings and can frequently resolve issues.
- Change the Sync settings for your calendars:
- Tap Settings > Mail, Contacts, Calendars.
- Scroll down to the bottom.
- Tap Calendars > Sync.
- If sync is set to All Events, set it to a specific duration, such as Events 1 Month Back. If it's set to a specific duration, set to All Events.
- Wait several minutes and try Refreshing Calendar again.
- Turn iCloud Calendar off and back on:
- Tap Settings > iCloud.
- Tap the Calendar slider off. Choose to delete data only if your data exists at icloud.com/calendar and/or one or more of your computers. Otherwise choose Keep Data.
- Wait a few minutes before turning the Calendar slider back on.
Have a good one,
The above didn't work for me.... so - perhaps my next option is to do what Howe7032 did and see if that works?
The invite I sent from my work Outlook email to my personal Gmail and accepted on my iPhone 4 has been moved, canceled, and accepted several times - each still appearing on the iPhone. Very frustrating indeed! Any other suggestions?