This may not work for everyone, but I was very frustrated and this worked for me. Below is from a top level support person at Google. The main point that worked for me was deleting my "accounts" on my iphone where I had set them up as Gmail and re-add them as exchange. example@googleapps.com username and password, server m.google.com
I tried adding an event afterwards and everything worked fine. Hopefully it works for others as this has been a nightmare for me for weeks.
Thanks, justin
There are a couple of known issues based on how the Apps account or the phone are configured.
These are the steps we recommend:
1. check the configuration of your device according to Apple Support articles athttp://support.apple.com/en-ie/HT203483 and http://support.apple.com/en-ie/HT202195.
2. make sure CalDAV/CardDAV is enabled in 'Device Management>Mobile>Device management settings' in order to fully utilize all Google Apps features on iOS devices. You can find more details on how to adjust your settings by visiting https://support.google.com/a/answer/6088059?hl=en
3. Be sure your Google account is added to your iOS device as an Exchange account.
And not as a Google Account.
Once your account is added on iOS device it is really important to access account configuration settings at https://m.google.com/sync/settings/ directly on your device using a Safari browser. These configuration settings are not global and the same process needs to be repeated on each device you wish to use with your Google Apps account.
To find more details and configuration steps please also visit these support articles
Set up Google Sync on iOS
https://support.google.com/a/users/answer/138740?hl=en and
Set up Google Sync with iOS Calendar
https://support.google.com/a/users/answer/139206.
If he is an admin he might be interested in these articles about the native iOS Management tools in the Admin Console.
Manage iOS Devices:
https://support.google.com/a/answer/6080045?hl=en&ref_topic=1734198