Yes, that endpoint is not working as expected. I opened this issue on Github - https://github.com/steemit/steem/issues/3223. It may provide you with some additional information.

Here's a not-so-good method to do it - https://busy.org/steemit/@steemitdev/additional-public-api-change#@singhpratyush/re-mosqueteros-re-singhpratyush-re-steemitdev-additional-public-api-change-20190111t092148496z.