Calendar In-App Notification

My issue is with my iCloud calendar not giving me notifications for calendar invite information. But I do get a badge notification on my Macbook pro calendar on OS x 10.11.3

Here's what is not working:

I enter an event on my iOS device or Macbook and invite people. They receive an email (non-cloud user) and click the Accept in the iCloud section of the email. On my Mac I get a badge on the Calendar app, but I get nothing on my iOS devices. If I open the calendar on my iOS devices and look at the event, I see the Accepted for that person. I have all the calendar notifications (badge, sound, banner) set on my iOS devices and I tried turning it off/on again but still no joy. Having the Show Invitee Declines setting on in Mail, Contacts, Calendars does work - if the choose Decline in the email notification I get an in-app on all my iOS devices as well as the Mac.

I have not idea why this is not working - running 9.2.1 on all devices. I'm not sure when as I just started doing invites on Jan 1st this year.

HELP!!!