When IncidentTicket data type is extended with custom data (for example by following this Connect article), Incident status in the Incident data (ImIncidentTicket.TicketStatus) is not properly changed from Resolved to Closed in the last stage of Incident Management flow, after Incident Resolution Confirmation (whether the resolution was confirmed or the confirmation times out).
Note that Process status (ReportProcess.Result) will be properly updated. Reports may use either one of the status values.
With extended IncidentTicket, Incident data does not get properly written back to the database before OnTicketClosed ruleset gets run.
The revised project for a fix can be found in KB Article TECH212326.
Please refer to that KB for the file.
ServiceDesk 7.5 SP1 with extended IncidentTicket.