So someone recommended a British TV series that was picked up by Netflix called "The End of the Fucking World".
I searched for it on Netflix on my Fire Stick and nVidia Shield and it said not found.
This evening I was pissing about with one of the Smart TVs (a Samsung) and noticed Netflix was on there. So I fired it up and searched for it and lo and behold it's there, and it plays.
I'm not sure if this is a workaround to bypass Netflix country restrictions, but you might want to try it if you find something is missing.