The mentions timeline via the REST API requires authentication as you
noticed. While you can use the search API for this, your results will be
limited by the tweets that enter the Search API's archive (more about what
you won't find in the Search API:
Gotcha,
So basically there is no way to grab only the @mentions for specific
handles? It was working just fine using the Search API until very recently
(past week) so I dont think the search limitations were the issue. Was the
archive purged in the past week? If so, is there any plan to