Show Quiz Results via Canvas REST API

[jwxzzalk]

I am trying to hide/show quiz results through Canvas REST API as guided here: https://canvas.instructure.com/doc/api/quizzes.html

I was able to change the "hide_results" from null to "always" (i.e., from showing the results to hiding the results). However, I failed to set it back (i.e., from "always" to null - from hiding results to showing). 

Here's the JSON data I tried to PUT. The response code was 200, but nothing changed. 

"quiz":
    {
    "hide_results": null,
    "show_correct_answers": true,
    "notify_of_update": false
    }
}

Any help would be appreciated!