Hi Kyle Perri,
If that truly is the JSON you are working with, then it would be expected that Geoevent is unable to construct geometry from it. There are no geometry fields to work with. Meaning, there are no X/Y or Lat/Lon fields that Geoevent would be able to read and create a geometry field from.
I have worked with that API before, and I have found that using this endpoint works much better for testing:
https://api.wheretheiss.at/v1/satellites/25544
As you see, it includes a latitude and longitude field that you can specify in the input connector configuration.
Keep in mind, however, that this API is known to intermittently go down and requests to certain endpoints sometimes result in a "Too many requests" error. Aside from that, it should work better for your testing.
If you are interested, you can also try using http://api.open-notify.org/iss-now.json for your GE testing. I have not personally experienced any outage issues with this one. However, this JSON is nested, so be mindful of that when specifying the JSON Object.
Hope this helps!
-Daniel