Taxonomy Terms node count of different content type along with zero count in a hierarchy
Check what you have set for the "no results" behaviour on that field. You will not want it set to "hide".

Also check if it displays in the views preview. If it displays there but not on your page then it may be that your template is checking if a field is blank and before deciding whether to show it - you could solve this by setting a default/no results value of "0"