DCH-Z510 siren—help needed

I’d suggest you use the SmartThings Classic app instead. Your tiles should all show up there, assuming there are no errors in your code.

The new app currently doesn’t work as well as the old app with custom groovy code, particularly when you’re trying to give a device a UI that doesn’t match one of the predefined templates. The thread below discusses how to get DHs to work with the new app, but even if you follow the suggestions I don’t think you’ll be able to get all of your buttons to show up.