Cannot get node JSON when logged in

I cannot access the JSON version of a node when logged in, anonymous access no problem. When logged in (including Administrator), the end point returns a 403. Updated to Drupal 8.2.1. The requesting page generated from a Module, same host.

Example request: /node/16?_format=json

Drupal version: 


Source: https://www.drupal.org/taxonomy/term/4/feed