Raspberry Pi issue: cannot create 4 SerialDevice objects with windows IoT Core

Question

I have a project that requires a Raspberry Pi 3 to read 4 USB inputs coming from 4 microcontrollers (SAMD21G mini breakout boards in particular). They are connected directly via USB. Raspberry Pi 3 is running Windows IOT core.

I have used microsoft's Serial Sample app with success on reading up to 3 inputs simultaneously.

The problem is everytime i try 4 USB inputs, the raspberry pi hangs and disconnects from remote debugging, then I have to restart the Pi so i can do remote debugging again.

Below is a snippet of the code where the problem occurs.

everything stops at the line: "serialPort4 = await SerialDevice.FromIdAsync(entry4.Id);"

I've already tried the program on a PC and it works fine. Has anyone encountered this issue? any help would be appreciated :)

   private async void comPortInput_Click_1(object sender, RoutedEventArgs e)
    {
        var selection = ConnectDevices.SelectedItems;

        if (selection.Count <= 0)
        {
            status.Text = "Select a device and connect";
            return;
        }



        DeviceInformation entry1 = (DeviceInformation)selection[0];
        DeviceInformation entry2 = (DeviceInformation)selection[1];
        DeviceInformation entry3 = (DeviceInformation)selection[2];
        DeviceInformation entry4 = (DeviceInformation)selection[3];

        try
        {

            serialPort1 = await SerialDevice.FromIdAsync(entry1.Id);
            serialPort2 = await SerialDevice.FromIdAsync(entry2.Id);
            serialPort3 = await SerialDevice.FromIdAsync(entry3.Id);
            serialPort4 = await SerialDevice.FromIdAsync(entry4.Id);

            if (serialPort1 == null || serialPort2 == null || serialPort3 == null || serialPort4 == null)
            {
                status.Text = "null";
                return;                  
            }


            // Disable the 'Connect' button 
            comPortInput.IsEnabled = false;

            // Configure serial settings
            serialPort1.WriteTimeout = TimeSpan.FromMilliseconds(3);
            serialPort1.ReadTimeout = TimeSpan.FromMilliseconds(3);
            serialPort1.BaudRate =9600;     //57600
            serialPort1.Parity = SerialParity.None;
            serialPort1.StopBits = SerialStopBitCount.One;
            serialPort1.DataBits = 8;
            serialPort1.Handshake = SerialHandshake.None;


            serialPort2.WriteTimeout = TimeSpan.FromMilliseconds(3);
            serialPort2.ReadTimeout = TimeSpan.FromMilliseconds(3);
            serialPort2.BaudRate = 9600;     //57600
            serialPort2.Parity = SerialParity.None;
            serialPort2.StopBits = SerialStopBitCount.One;
            serialPort2.DataBits = 8;
            serialPort2.Handshake = SerialHandshake.None;


            serialPort3.WriteTimeout = TimeSpan.FromMilliseconds(3);
            serialPort3.ReadTimeout = TimeSpan.FromMilliseconds(3);
            serialPort3.BaudRate = 9600;     //57600
            serialPort3.Parity = SerialParity.None;
            serialPort3.StopBits = SerialStopBitCount.One;
            serialPort3.DataBits = 8;
            serialPort3.Handshake = SerialHandshake.None;


            serialPort4.WriteTimeout = TimeSpan.FromMilliseconds(3);
            serialPort4.ReadTimeout = TimeSpan.FromMilliseconds(3);
            serialPort4.BaudRate = 9600;     //57600
            serialPort4.Parity = SerialParity.None;
            serialPort4.StopBits = SerialStopBitCount.One;
            serialPort4.DataBits = 8;
            serialPort4.Handshake = SerialHandshake.None;


            // Create cancellation token object to close I/O operations when closing the device
            ReadCancellationTokenSource = new CancellationTokenSource();
            if (serialPort1 != null || serialPort2 != null || serialPort3 != null || serialPort4 != null) //|| serialPort4 != null
            {
                // Create the DataWriter object and attach to OutputStream
                dataWriteObject1 = new DataWriter(serialPort1.OutputStream);
                dataWriteObject2 = new DataWriter(serialPort2.OutputStream);
                dataWriteObject3 = new DataWriter(serialPort3.OutputStream);
                dataWriteObject4 = new DataWriter(serialPort4.OutputStream);
                //Launch the WriteAsync task to perform the write
                await WriteAsync();
            }
            else
            {
                status.Text = "Select a device and connect";
            }

            Listen();
        }
        catch (Exception ex)
        {
            status.Text = ex.Message;
            comPortInput.IsEnabled = true;
            //sendTextButton.IsEnabled = false;
        }
    }