Anyone know what a calendar item with an eventtype of 5 means? I think its to do with specific instances of a recurring event but am not sure and can't seem to find a definitive list anywhere that includes this particular one?
I have seen this event type value when using the expand recurrence option in a CAML query. Each occurrence in the series, except series exceptions or deletions, will have an EventType value of 5.
Are you sure that the EventType is 5 and that this has been setup by SharePoint - rather than modifed by non OOTB code?
I've only ever see EventTypes of 0-4 as detailed here - and I've done a lot of work with recurring events.
If it showing 5 can you detail the recurrence pattern and any exceptions (deleted/modified) instances so that we can try to reproduce the problem.