It is understood the investigation by Deloitte has been running since July or August.
It was expected to cover issues such as transparency of communication with elected representatives.
The Otago Daily Times asked why it was taking so long for a report to be completed and if the council had been advised of any reason for delays.
A council spokesman said the council was not in a position to comment.
The council has not acknowledged the existence of the investigation.
The council was asked in November whether a firm had been appointed to look into management practices and when a result was expected.
It had no response to the query.
Another report — an investigation by Maria Dew, KC, into bullying claims — was not able to be viewed by most councillors last year.
The council has not said whether this situation would be avoided next time.
