TotalMatching shows 0

Hi!

I am new to Find, and I have recently taken over a solution based on Find. We are experiencing a problem with a counter, that works on and off.

 IContentResult<T> result = _findClient.Search<T>(Language.Norwegian)
                .ApplyQueriedSearch(query)
                .FilterByAncestor(rootContentLink)
                .FilterByCategories(categories, categoryMatchOperator)
                .FilterForVisitor()
                .Take(1)
                .StaticallyCacheFor(TimeSpan.FromMinutes(5))
                .GetContentResult();
            return result.TotalMatching;

The property "TotalMatching" shows either correct number, or 0, on and off. The indexing job goes every 2nd hour.

Does anyone have a clue what might be wrong?