I don’t recall ever seeing that message, so I appreciate the screenshot! 
I wonder if that’s an iOS-specific error. The only possible recent mention that comes to mind for me is this:
I wonder if that’s the same issue and if it’s some kind of server-side and/or iOS-specific problem. I use Android and in the current production app just tapped through all the Plugs and Plug Outdoors that I currently have powered. I was doing this on the Devices tab and was unable to reproduce this issue.