Insert liveCuePoints in live broadcast - getting error 403 Forbidden - youtube

Question

We have a verified app with the following scopes:
https://www.googleapis.com/auth/youtube.force-ssl
https://www.googleapis.com/auth/youtubepartner
https://www.googleapis.com/auth/youtube
This means we can use the YouTube Data API and YouTube Content ID API (for YouTube Partners).
We are trying to do ad inserts (insert LiveCuepoints) for a live broadcast on a YouTube partner channel, which is connected via our verified app. We are getting the following error when we use the LiveCuepoint insert API endpoint:
Request
POST /youtube/partner/v1/liveCuepoints?channelId={channelId}&onBehalfOfContentOwner={contentOwnerId} HTTP/1.1
Authorization: Bearer {accessToken}
Content-Type: application/json; charset=utf-8
Host: www.googleapis.com
Content-Length: 57
{"broadcastId":"{broadcastId}","settings":{"cueType":"ad"}}
Response
{
"error": {
"code": 403,
"message": "Forbidden",
"errors": [
{
"message": "Forbidden",
"domain": "global",
"reason": "forbidden"
}
]
}
}
Other requests (with the same credentials) to the YouTube Content ID API (such as listing contentOwners or listing liveBroadcasts) are working fine and without errors.
We’ve tried debugging this issue for many hours, researched online and tried different solutions but couldn’t get this to work. Is there a special scope, setting or access needed to do ad inserts in a live broadcast? Is anyone having working example code to do liveCuepoint inserts?

Answer 1

For anyone interested: I found the solution.
We connected (via our verified app) as a channel. This was a mistake, you have to authenticate with an account, and this account must have administrator rights.
Now you receive an access token which can access all content owners and channels connected to that account. Inserting liveCuePoints now works fine!