Reply on message failing

Hi team,

I am trying to reply to a topic present in Q&A board. Here are the API details:

Method : POST

Header:

Content-Type : multipart/form-data; boundary=ttO7xyWXN8H2NgoNDgScicCBXbMZoLdb0Z

Enpoint: 
http://arrivalpreprod.stage.lithium.com/restapi/vc/messages/id/11585/reply?restapi.session_key=<session-id>&restapi.response_format=json&restapi.response_style=view&restapi.response_format=json&restapi.response_style=view&restapi.response_format=json&restapi.response_style=view&restapi.response_format=json&restapi.response_style=view

Form Parameters: (key - Value)
message.subject - Re: Post 2
message.body  - <p>Hello metestigg Q&amp;A :D</p>
message.is_draft - false
qanda.is_answer - true

Response:
{"response":{"status":"error","error":{"code":303,"message":"Permission Denied"}}}

if we do not pass the qanda.is_answer  parameter the API call is working fine.

If we remove the