Sorry, I didn't fully test @bravenel's asynchttp changes. It looks like the response from asynchttp is slightly different and also not working for this case.
According to the Documentation AsyncResponse follows SmartThing's implementation and now has a getJson() method that returns the parsed JSON object. getData() returns the raw unparsed string which is why that error is displayed. I tried changing it to the new parameter (response.json) but it's returning null.
[app:162] 2018-06-29 15:34:19.628: Harmony - response.json: null
[app:162] 2018-06-29 15:34:19.626: Harmony - response.data: {hubs={11...[truncated rest of data]
@bravenel, do you know if there's any issues with the getJson() method on an AsyncResponse?
I have rolled back to the syncronous http methods for now since these were parsing into JSON correctly and have commited it to Github (only a change to the app).
