Missing data on applying legend

I don't really understand why it happens. Seen it before but haven't figured it out yet. 

Below I have a stacked bar chart where cases are assigned to people (which are on the categories). 

Now I was curious to the distribution within this context on some variables. Among one was country. When I add this field (same table), the totals become less. 

The sort on the stacked chart is still descending on total cases. Blank is a value in the legend. 'Show items with no data' is turned on. When I change the stacked bar chart into a matrix, the totals do show the correct figures.

Who knows what's going wrong here?