Interesting, so there are actually no results that have been geocoded in the result set, so if you have changed providers, then they aren’t providing any functionality for search at the moment.
This has resulted in at least a 10x drop in results. Only a relatively small portion of people have either a lat/lon in their profile, or attached to their tweet. The above search I provided for the web search interface is mirroring the problem :
https://twitter.com/search/realtime?q=near%3Amelbourne&src=typd
Thanks!