SimpleJson data source /query - no response

(Howdy All, First post here; experienced admin and programmer, but new to Grafana)

Attempting to set up a SimpleJson data source. Nothing is appearing when I try to select metrics

 - Data source save and test message: "Data source is working"
 - Panel -> Edit -> timeserie -> select metric: // Nothing appears

I suspect an issue with the REST interface. Given that SimpleJson requires these routes: /, /search, /query, /annotations [1], I tried to test with cURL, like so:

$ curl -s -X GET 'http://localhost:9100/api/routes'

This returns a list of routes, including:

    "path": "/grafana/query",
    "method": "POST",
    "has_arg": false

When I try to invoke the search request, which is “used by the find metric options on the query tab in panels”:

$ curl -v -X GET 'http://localhost:9100/api/grafana/search'

I get this… shouldn’t metric options be returned here?

$ curl -v -X GET 'http://localhost:9100/api/grafana/query'
* About to connect() to localhost port 9100 (#0)
*   Trying
* Connected to localhost ( port 9100 (#0)
> GET /api/grafana/query HTTP/1.1
> User-Agent: curl/7.29.0
> Host: localhost:9100
> Accept: */*
< HTTP/1.1 200 OK
< Cache: no-cache
< Content-Type: application/json
< Date: 2019-03-20T14:51:01.138Z
< Access-Control-Allow-Origin: *
< Access-Control-Allow-Methods: POST
< Access-Control-Allow-Headers: accept, content-type
< Content-Length: 0
* Connection #0 to host localhost left intact

Testing these routes in browser also yields no errors, but also no response. Just a blank screen with a “This request has no response data available”

I’m puzzled, stuck, and unfamiliar with what to expect. Am I correct in isolating the issue to the REST response? Am I testing this properly? Is it Grafana, the REST interface, or SimpleJson? Do I need to set up a query; I though that the /search REST endpoint is to return metrics. Is there a way for me to test this more effectively? Thx, Keith :^)