When creating a project in Project Designer 1.26.0 which contains a device with volume level control and that sequence is being used on a button or slider, you will end up with a control system that freezes up.
When volume level control sequence is added to a button or slider it defaults to 100 seconds delay in between each volume step command.
Change it back to somewhere in between 0.1 to 0.5 seconds and upload it again and project will be back up and running in no time.
Bug in Project Designer 1.26.0. Was fixed in Project Designer 1.27.0 released on January 4'th - 2021.