Building and running an app shows at some point in the process the "Uploading file" modal window. In my case the PBX had an unknown problem. Even the AppClient couldn't start the Devices app. I needed to restart the PBX then the Devices app could start. However, the "Uploading file" still did not respond and blocked the whole Visual Studio 2019. I had to end Visual Studio in the Windows Task Manager. Please add a way to cancel the process manually or automatically after some time.