How do I show the number of nodes using a taxonomy term?
The following worked for me in Drupal-8.0.6.

Note that for some reason 'Content NID' is not offered as a field for the 'Content with term' relationship, so I used UUID instead and it worked.


Create a Taxonomy Term view (with a field Taxonomy term: name, usually linked to the term page)
Relationship > Taxonomy term: Content with term (will be called node).
Advanced: Use aggregation: Yes
Add Field > Content: UUID with relationship node
Aggregation type for UUID = Count


You may have to play with COUNT vs COUNT distinct

If you want tbe count to appear in brackets like this:

linked_term (count)


On UUID field use Rewrite results:

({{ uuid }})


Note that it is using the new Twig template language notation.