iCloud to iCloud not working – Gmail invites instead

I use my Google Apps email for my primary iCloud account, and recently switched from iCloud to Google Calendar and back to iCloud again. However, when I am invited to an event to my iCloud Calendar, it goes to my Gmail account rather than as an event invite via iCloud. How can I rectify this without changing my email?

I can send iCloud invites to other people, they just can’t send them to me.

• I’ve gone so far as to disable and uninstall Google Calendar on my Google Apps domain.
• I have gone to iCloud.com and made sure I am able to receive event invites directly to my devices.
• I’ve checked preferences on my Mac, iPhone, etc. to make sure I can receive these invites.

Would this be a problem with my iCloud account, or would it be as simple as going onto my girlfriend’s laptop and clearing out autocomplete email addresses and seeing if that works? All help is welcome.

Thanks!