We had an extended internet outage in our area last night. When I woke up the internet connection and house WiFi were back up. However I was unable to connect to any camera that was part of a group. I had to flatten (expand) the groups and reconnect to each camera one by one.
Not a bug per se but odd behavior. Would really suck for someone that had a lot of cameras.
I have also noticed that occasionally cameras will not connect in group mode, but opening in single mode will. But sometimes force quitting the app and restarting it solves this without having to open them all in single mode.