Ad blockers such as uBlock and AdBlockPlus block all AJAX requests to the pageviews API. Try uBlock in Firefox and perform requests on RESTBase. These ad blockers are very popular and cause tools like Pageviews Analysis to fail.
See comment from @MusikAnimal below and update the on-wiki docs + the hyperswitch documentation so that others who run into this problem don't get stuck.
Consider making a proxy on the front-end from /pv to /pageviews to avoid this issue, but if ad-block software starts blocking /pv just give up the fight :)
Possible alternative layouts that aren't blocked
- possibly, later:
The exact routes that most ad blockers are currently targeting can be found here.