Facebook Calendar integration not working

Is anyone else having issues with Facebook calendar events not displaying on their iPhone calendar?

When I first updated to ios6 i used to get Facebook banners automatically appearing for each date on which I had a Facebook event. Now I get nothing. The Facebook Events calendar is ticked under the calendar list and the access to calendar setting is switched to On under Settings>Facebook.

I would be grateful for any suggestions; at the moment I am using a manual subscription calendar to get round the problem, but just wondering if there is any way to return my iPhone to normal Facebook integration.

Thanks.