We have the same issue as CBattles reported. We were creating events on existing contacts just fine in test and it all of a sudden quit working. I’m still getting the 200 ok repsonse though. Here is the URL
@Rambo the report for the event does not update in real time. You can see the current delay for the report at the bottom of the left sidebar when viewing the report.
Are you seeing the event completions at all in the event report? You should be able to see the events in close to real-time using the activity log linked in the left sidebar when viewing the report for the event.