Youtube Data API v3 PlaylistItems update not working for Watch Later playlists

Recently, the youtube.playlistItems.list doesn't fetch a playlist item that is suitable for the youtube.playlistItems.update when listing the watchLater playlist. Its works perfectly for playlist that aren't under the relatedPlaylists category of a channel. (e.g. History, favourite, likes etc.)

My list response looks like this:

{
 "items": [
  {
   "id": "V0xWWlh5N2JrM0JSTjAtcDJVUmdjc3JRLjZCM0UwMDFFNUU3NzYzNjc=",
   "snippet": {
    "publishedAt": "2016-03-21T19:04:22.000Z",
    "title": "One Word - Episode 38: Skin Tone (Black Women)",
    .
    .
    .
    "channelTitle": "Ryan Carter",
    "playlistId": "WLVZXy7bk3BRN0-p2URgcsrQ",
    "position": 0,
    "resourceId": {
     "kind": "youtube#video",
     "videoId": "0gYgzN6B0y4"
    }
   }
  },

But when I use those values:

PUT https://www.googleapis.com/youtube/v3/playlistItems?part=snippet%2Cid&key={YOUR_API_KEY}

{
 "id": "V0xWWlh5N2JrM0JSTjAtcDJVUmdjc3JRLjZCM0UwMDFFNUU3NzYzNjc=",
 "snippet": {
  "playlistId": "WLVZXy7bk3BRN0-p2URgcsrQ",
  "resourceId": {
   "kind": "youtube#video",
   "videoId": "0gYgzN6B0y4"
  }
 }
}

I get:

404 null

- Show headers -

{
 "error": {
  "errors": [
   {
    "domain": "youtube.playlistItem",
    "reason": "playlistItemNotFound",
    "message": "Playlist item not found."
   }
  ],
  "code": 404,
  "message": "Playlist item not found."
 }

}

• Down for just me?
• Have Google blocked updates for the Watch Later playlist?
• Is the service broken?