appium: Parallel Execution, Appium hangs on first command (after driver init)

The problem

Working fine on one device, but hangs forever on the first command with two or more. Example commands that hang for 60 seconds… is this because of parallel execution? How to work around

• getDeviceSize()
• element.Click()
• findElementsById()

Environment

• Appium 1.6.5
• Windows/Linux

Link to Appium logs

https://gist.github.com/gamesguru/7b740c93ea0683962006765699fe87bb

Code To Reproduce Issue [ Good To Have ]

 private void Bw_DoWork(object sender, DoWorkEventArgs e)
        {
            int i = 0;
            foreach (string serial in nativeFuncs.initialSerials)
            {
                nativeFuncs.statusDict[serial] = "loading";
                nativeFuncs.appiumLogDict[serial] = "...starting appium...\n";
                nativeFuncs.portDict[serial] = 4723 + i;
                comboBox1.Items.Add(serial);
                i++;
            }
            //comboBox1.SelectedIndex = 0;
            nativeFuncs.setDevStats();
                     

            //runs the main tests
            Parallel.For(0, nativeFuncs.initialSize, new ParallelOptions { MaxDegreeOfParallelism = 4 }, z =>
            {
                string s = nativeFuncs.initialSerials[z];
                pReader.cmd($"/c appium -a 127.0.0.1 -p {nativeFuncs.portDict[s].ToString()}", s, true);

                DesiredCapabilities capabilities = new DesiredCapabilities();
                capabilities.SetCapability("udid", s);                                  //serial
                capabilities.SetCapability("deviceName", nativeFuncs.devNameDict[s]);   //SM-J327P (aka productModel)
                capabilities.SetCapability("appPackage", appPackage);
                capabilities.SetCapability("appActivity", appActivity);
                capabilities.SetCapability(MobileCapabilityType.NoReset, true);
                capabilities.SetCapability(MobileCapabilityType.FullReset, false);

                nativeFuncs.cmdWorkerDict[s].RunWorkerAsync();
                nativeFuncs.selfLogDict[s] += "starting appium log..\n";
                nativeFuncs.selfLogDict[s] += $"on port {nativeFuncs.portDict[s].ToString()}..\n";
                nativeFuncs.statusDict[s] = "Starting";
                try { nativeFuncs.driverDict[s] = new AndroidDriver<AndroidElement>(new Uri("http://127.0.0.1:" + nativeFuncs.portDict[s].ToString() + "/wd/hub"), capabilities); }
                catch (Exception ex) { nativeFuncs.selfLogDict[s] += printE(ex); }
                AndroidDriver<AndroidElement> driver = nativeFuncs.driverDict[s];
                if (driver == null)
                {
                    nativeFuncs.appiumLogDict[s] += "\n\nAppium failed to connect..";
                    //nativeFuncs.s
                    return;
                }

                driver.Manage().Timeouts().ImplicitWait = TimeSpan.FromSeconds(7);

                //grabs screen size
                //nativeFuncs.hDict[s] = driver.Manage().Window.Size.Height;
                //nativeFuncs.wDict[s] = driver.Manage().Window.Size.Width;
                //nativeFuncs.yDict[s] = nativeFuncs.hDict[s] / 2;
                //nativeFuncs.xDict[s] = nativeFuncs.wDict[s] / 2;

                //nativeFuncs.selfLogDict[s] += $"Height: {nativeFuncs.hDict[s]}, Width: {nativeFuncs.wDict[s]}";
                //Thread.Sleep(700);

                nativeFuncs.selfLogDict[s] += "\nAppium started, logging into OneControl...";
                nativeFuncs.statusDict[s] = "First run";
                nativeFuncs.setDevStats();

                if (!nativeFuncs.devNameDict[s].Contains("OCTP"))
                    testMethods.pinScreen(s);

                testMethods.TestLighting(s);
            });