Search hanging despite successful api call

Mapbox version: 0.44.1
Geocoder version: 2.2.0

I'm attempting to get the geocoder to work, but it consistently hangs despite the network request returning successful:

Additionally I've tracked down that this then clause never gets called. I tried digging into the client to figure out why but didn't make much progress: https://github.com/mapbox/mapbox-gl-geocoder/blob/master/lib/index.js#L166. Any guidance would be helpful!

My setup is local and the code I'm using to call it is:

map.addControl(new MapboxGeocoder({
        country: 'US',
        accessToken: AccessToken,
 }));

Start by reproducing the reported setup with MapboxGeocoder, then inspect lib/index.js around line 166 where the unresolved then clause is mentioned. Trace why the successful request does not complete the search, and consider the issue done when the same configuration finishes instead of hanging.