Hi, Odd problem. I'm on BIS and have sync'd my 3 Gmail accounts to the phone. My calendar is set to sync and seems to work. But, I can't send invites. I can create a new appointment but I can't send them as meeting requests.
I've made sure the default CICAL is set to my Gmail account and all the service books are present.
I just don't have a "create invite" menu item & the app participants button is greyed out.