As you can see, in the app if I try to adjust my existing restriction to start at 7:05am instead of 7:20am, it will not let me make the change because it says the start time must be before the end time (which it is).
I was able to change in beta web app, so this looks like a bug w the iOS version of the app.
Beta app
https://www.netrohome.com/webui/index#