-ms and -si parameters in OPC Publisher

Question

Hi,
I am collecting data from OPC Server via OPC Publisher onto to IoT hub
I need to collect data at 20s frequency and set OpcPublishiNterval as 20000 in PublishedNode.json as shown below

   {
    "Id": "ns=3;i=1008",
    "DisplayName": "F101A",
    "OpcPublishingInterval": 20000
  },

It works fine and I get messages every 20S on IoT hub
But I wish to consolidate the content in each message so the message is sent out by publisher only when it reaches 4Kb limit as standard Azure message is 4Kb and subscription is based on no of messages sent every day

So i set the -ms =4096 while running the publisher . set -si =0 as shown below
{
"Hostname": "publisher",
"Cmd": [
"--pf=/appdata/publishednodes.json",
"--aa",
"--si=0",
"--ms=4096",
"--ct=120"
],
"HostConfig": {
"Binds": [
"/home/ubuntu/Downloads:/appdata"
]
}
}

However get this error for any value set for ms other than 0

[10:20:56 WRN Microsoft.Azure.IIoT.OpcUa.Protocol.Services.DefaultSessionManager] Failed to create session 'b2c224f8eaa44c2bc65884d1d546a9a378e1771c' due to One or more errors occurred. (BadRequestTimeout) [10:21:06 INF Microsoft.Azure.IIoT.OpcUa.Protocol.Services.DefaultSessionManager] Creating session 'b2c224f8eaa44c2bc65884d1d546a9a378e1771c' for endpoint 'opc.tcp://ip-172-31-79-206.ec2.internal:53530/OPCUA/SimulationServer'...

Also tried changing -ct option as error was on create session timeout -but that did not resolve the issue either

Any help is appreciated

THanks