Pass a token via the addition of a URL query parameter with "token=tokenvalue." in Azure Media Service not working - azure-media-services

Question

Trying to stream a video from Azure Media Service into a Xamarin.Form application.
The asset is protected with a JWT token.
I use the following code to generate the token:
private string GetJWT(string PrimaryKey) {
var tokenSigningKey = new SymmetricSecurityKey(Convert.FromBase64String(PrimaryKey));
SigningCredentials cred = new SigningCredentials(tokenSigningKey, SecurityAlgorithms.HmacSha256);
JwtSecurityToken token = new JwtSecurityToken(
issuer: "xxx",
audience: "yyy",
claims: null,
notBefore: DateTime.Now.AddMinutes(-5),
expires: DateTime.Now.AddMinutes(60),
signingCredentials: cred);
JwtSecurityTokenHandler handler = new JwtSecurityTokenHandler();
return handler.WriteToken(token);
}
The URI for the asset is like : https://xxx.streaming.media.azure.net/12222-1565-232323-a5b8-c10e148273ae/Test.ism/manifest(format=m3u8-cmaf,encryption=cbc)
If I use Azure Media Player (https://ampdemo.azureedge.net) to test the URI and the AES token, it works fine. So I guess there is no problem with the token itself...
The documentation (https://learn.microsoft.com/en-us/azure/media-services/latest/security-pass-authentication-tokens-how-to#pass-a-token-via-the-addition-of-a-url-query-parameter-with-tokentokenvalue) says that the following code should work to send the token directly with the url.
I need to do this as with Xamarin.Forms and MediaElement, I can't send the token in a header request. So I need the querystring option...
string armoredAuthToken = System.Web.HttpUtility.UrlEncode(authToken);
string uriWithTokenParameter = string.Format("{0}&token={1}", keyDeliveryServiceUri.AbsoluteUri, armoredAuthToken);
Uri keyDeliveryUrlWithTokenParameter = new Uri(uriWithTokenParameter);
player.Source = keyDeliveryUrlWithTokenParameter; (player is a MediaElement control)
But the video is never loaded.
In my opinion there is an error, it should be {0}?token={1} instead of {0}&token={1}.
But that doesn't work neither.
If I test with VLC the https://xxx.streaming.media.azure.net/12222-1565-232323-a5b8-c10e148273ae/Test.ism/manifest(format=m3u8-cmaf,encryption=cbc)?token=zzzzz, it doesn't work neither.
I presume there is a problem with token in the querystring, as if Azure can't read it.