Class B multicast

Hi,

With a Class B multicast downlink, I need to schedule the downlink packets by adding the field "absolute_time". For example:

    "f_port": 4, 
    "frm_payload":"", 
    "priority": "NORMAL", 
    "class_b_c": { 
      "gateways": [ 
        { 
          "gateway_ids": { 
            "gateway_id": "..." 
          } 
        }
      ],
      "absolute_time": "2022-06-23T10:35:55.809072304Z"
    } 
}]}

When specifying such time for a Class B multicast device, the message gets queued but never sent.

I tried the same with a Class C unicast device. Then the message is queued, however, 5 secs before the time set, I get the failure:

..."error":{"namespace":"pkg/networkserver","name":"absolute_time","message_format":"invalid absolute time set in application downlink","code":3}}}

Any thoughts on what I’m missing here?