I've been a happy user of [the /2.1/similar Stack Exchange API][1] for a while. But, at some point within the last 24 hours, or so, it started returning empty results (but otherwise reporting everything as good).

I am seeing the same behavior from [the doc examples][2].
 
It does not matter which site I search or which search terms I use. And yes; I triple checked that I am not busting the rate limit or otherwise getting errors reported :-)


  [1]: https://api.stackexchange.com/docs/similar
  [2]: https://api.stackexchange.com/docs/similar#order=desc&sort=activity&title=help%20with%20stuff&filter=default&site=stackoverflow&run=true