Meeting requests sent with iOS7 don't work correctly

When I create a meeting with invitees in an Exchange calendar on iOS7.0.2 (iPhone4), the receiver get's a mail with a "meeting.ics" file.

When opened, it's not possible to select accept,decline, or maybe, but only select "add to calendar" on their iPhone 5 (still on iOS 6.1.3).

When the same meeting invite is opened in Outlook it even says: "Not supported calendar message.ics".

This worked fine when creating meeting with invites in iOS 6.1.3.

It seems the meeting request format is messed up with iOS7... Anyone else seeing this?

I can't find any setting in iOS7 about meeting invite formats.