I have exactly the same problem. On both my iPad and my iPhone, the Home app regularly freezes and becomes completely unresponsive when I’m editing a scene. I’m using the latest version of the app and the latest version of iOS.
The only solution seems to be to force-quit the app, reopen it, then edit the scene in little steps, closing the edit dialog between each step.
This bug appeared fairly recently. VERY irritating.
When is Apple going to fix it? Do they need any more information to reproduce it?