Captions video not getting generated with V2 video create API

I am trying to create a video with captions using the create video V2 API but captions are not getting generated with the video. Can anyone please help me and let me know what am I doing wrong. Used below curl to generate the video

{
  "video_inputs": [
    {
      "character": {
        "type": "avatar",
        "avatar_id": "*******************", // hidden for security reasons
        "avatar_style": "normal"
      },
      "voice": {
        "type": "text",
        "input_text": "This is a video with captions",
        "voice_id": "*******************" // hidden for security reasons
      }
    }
  ],
  "title": "Video with a caption",
  "dimension": {
    "width": 1280,
    "height": 720
  },
  "caption": true,
  "open_caption": true // used this as well after using caption but still no success

}