OK,

I have re-written like this:

// This example logs the mc Unique IDentifier (mcUID), Temperature and battery Voltage
// to MQTT.
//

Class Events
    Shared Event Publish() RaiseEvent Every 1 Minutes
        LedGreen = True
        Dim Sensors As Values = New Values
        Lplan.Publish("MCThings/" + Sensors.mcUIDString + "/Uptime", Sensors.GetUptime)
        Lplan.Publish("MCThings/" + Sensors.mcUIDString + "/BatteryVoltage", Sensors.GetBattVoltage)
        Lplan.Publish("MCThings/" + Sensors.mcUIDString + "/Temperature", Sensors.GetTemp)
        LedGreen = False
    End Event 
End Class

Class Values   
    Public mcUIDString As String = Device.mcUID().ToString()
   
    Public Function GetTemp() As ListOfByte
        //LedGreen = True
       
        Dim TempC As Float = TempSensor.GetTemp
        Dim TempString As String = TempC.ToString()
        Dim Temppayload As ListOfByte = New ListOfByte()
       
        Temppayload.Add(TempString)
        Return Temppayload
        //Lplan.Publish("MCThings/" + mcUIDString + "/Temperature", Temppayload)
       
        //LedGreen = False
    End Function
   
    Public Function GetUptime() As ListOfByte
        //LedRed = True
       
        Dim uptime As Integer = Device.Uptime()
        Dim uptimeString As String = uptime.ToString()
        Dim Uptimepayload As ListOfByte = New ListOfByte()
       
        Uptimepayload.Add(uptimeString)
        Return Uptimepayload
       
        //Lplan.Publish("MCThings/" + mcUIDString + "/Uptime", Uptimepayload)
       
        //LedRed = False
    End Function
   
    //Shared Event CheckVoltage() RaiseEvent Every 2 Days
    Public Function GetBattVoltage() As ListOfByte
        Dim BattVolt As Short = Device.BatteryVoltage
        Dim BattString As String = BattVolt.ToString()
        Dim Battpayload As ListOfByte = New ListOfByte()
        Battpayload.Add(BattString)
        Return Battpayload
        //Lplan.Publish("MCThings/" + mcUIDString + "/BatteryVoltage", Battpayload)
        //If BattVolt < 2200 Then
        //Lplan.IFTTT("YOURIFTTTKETHERE", "ProductionRoomBattery/YOURTOPICHERE")
        //Else
       
        //End If
       
    End Function
End Class
This works - sort of (still getting unexplained resets every minute or so).

Good thing you don't need to be a programmer to figure this out, or we would all be stuck.