It was working really well in both 12.6.4 and 14.1, which we recently have been upgrading from.
I think the major difference is the handling of Offline Endpoints, which has been changed in recent versions. Previously we ended up with an event failing (and thus completing), when an endpoint was offline. Now we enter this partially completed state, because CA IDM will leave the task 'Waiting for resubmission' for the offline endpoints, that it fails to communicate with.
This means that the events will never complete - and our policies will then not fire.