Multicast Class-C downlink scheduler problem

Hi,

I’m testing a multicast mode with class-c device using LoRaMac-node. My gateway is based on RAK22435 board. First I created multicast group and added my one device to it. To schedule downlink I’m using API provided with loraserver and following JSON:

{
  "multicastQueueItem": {
    "data": "1234",
    "fCnt": 0,
    "fPort": 2,
    "multicastGroupID": "32e2fd82-1f5e-4035-93e9-9a2a598e1420"
  }
}

Response is always

{
  "fCnt": 0
}

I checked with SDR and nothing is being transmitted on 869525000 Hz from gateway.
Logs from loraserver:

Jul 18 09:58:07 rak-gateway-dev-1 loraserver[748]: time="2019-07-18T09:58:07Z" level=info msg="finished unary call with code OK" grpc.code=OK grpc.method=GetMulticastGroup grpc.service=ns.NetworkServerService grpc.start_time="2019-07-18T09:58:07Z" grpc.time_ms=2.607 peer.address="[::1]:44960" span.kind=server system=grpc
Jul 18 09:58:07 rak-gateway-dev-1 loraserver[748]: time="2019-07-18T09:58:07Z" level=info msg="multicast-group updated" id=32e2fd82-1f5e-4035-93e9-9a2a598e1420
Jul 18 09:58:07 rak-gateway-dev-1 loraserver[748]: time="2019-07-18T09:58:07Z" level=info msg="finished unary call with code NotFound" error="rpc error: code = NotFound desc = object does not exist" grpc.code=NotFound grpc.method=EnqueueMulticastQueueItem grpc.service=ns.NetworkServerService grpc.start_time="2019-07-18T09:58:07Z" grpc.time_ms=15.299 peer.address="[::1]:44960" span.kind=server system=grpc

Questions:

  1. Is it possible to send downlink in multicast even if devices are not joined to it (only added in multicast config). Maybe this is issue with device not gateway. But it’s weird that gateway is not transmitting anything and fCnt is always 0
  2. Are there any other steps that I can perform to debug this issue?

EDIT
I’m using newest lora-app-server and loraserver

SOLUTION

Am I the only one with this issue?
@brocaar do you have any idea what might go wrong? I also disabled mac commands in loraserver config, didn’t help.