FOR ANYONE WHO HAS BEEN UNABLE TO CREATE A CAMERA GROUP:
The latest version of my API Browser+ web app adds a new feature to create a camera group. So if this ability has disappeared from your SmartThings app, try using this tool so you can get your camera group created. Note that you will need at least two camera devices to create a group. If needed, you can create a virtual camera device using my vEdge driver, and include it in your group.