AudioVideoSample throws a 500 internal server error on changeRole

Describe the issue
I am trying to use 'changeRole' on the audiovideo bot after the bot has joined and starts playing the video.

Expected behavior
This should stop playing the video and I expect the following line to get triggered logging something

Call ID
461f1100-c139-427c-a0ec-33ab2bbc1d49

Logs
$>2019-07-05T19:19:26.2905073Z Info: LoggingMessageHandler.cs:167 SendAsync
TransactionDirection: Incoming
TraceType: HttpResponse
ResponseTime: 213
request: POST https://trusthive.com/calls/461f1100-c139-427c-a0ec-33ab2bbc1d49/changeRole
response: 500 InternalServerError
headers:
Content-Type: text/plain; charset=utf-8
$>2019-07-05T19:19:26.0873716Z Info: LoggingMessageHandler.cs:138 SendAsync
TransactionDirection: Incoming
TraceType: HttpRequest
request: POST https://trusthive.com/calls/461f1100-c139-427c-a0ec-33ab2bbc1d49/changeRole
headers:
origin: (redacted)
postman-token: (redacted)
Cache-Control: no-cache
Connection: close
Accept: /
Accept-Encoding: (redacted)
Accept-Language: (redacted)
Host: trusthive.com
User-Agent: Mozilla/5.0,(X11; Linux x86_64),AppleWebKit/537.36,(KHTML, like Gecko),Chrome/74.0.3729.131,Safari/537.36
Content-Length: (redacted)
Content-Type: application/json
Additional context
Add any other context about the problem here.

If I leave the call and rejoin the call, at least the video stops playing. And even though I have video enabled, there is nothing in the logs if I sent the changeRole request again.

Start with the AudioVideoSample changeRole request and the LoggingMessageHandler.cs entries at lines 138 and 167; reproduce the POST using the call ID and inspect the returned 500 response. Done means changeRole stops the video as expected and the relevant logging behavior is observed without an internal server error.