"Try it Out" button doesn't work for operational datastore query

"Try it out" functionality does not work for querying the operational data store.

This was encountered through:
1) Browse to http://<controller-ip>:8181/apidoc/explorer/index.html
2) Select "Mounted Resource"
3) Select the 1st one "DataStores" and there are 3 queries underneath.
The first and 3rd one work, but 2nd one("Queries the operational (running) datastore on the mounted hosted") does't return.
Once you click the "Try it Out", it won't return anything.

However, the actual URL works -
http://10.18.162.121:8181/restconf/operational/opendaylight-inventory:nodes/node/controller-config/yang-ext:mount/

This is believed to be an issue with how apidocs queries restconf, rather than an issue with restconf itself.