How to hide an empty view block when using a contextual filter and NO file fields?
Add  another filter it's not important which field , as example if you have Content:title ( or any field you have in fields row) and  set filter is it's not empty. 

The mechanism is simple, contextual filter cause view not consider as empty even thought there is no any row, and when you add a filter on a field that not exists it cause view considered as empty. So only add one of your view field to  filter and  check if it is not empty