Hi, so sorry for the inconvenience,
First of all, always feel free to ask questions here!
Now, just to verify, you have:
- Enabled the registry flag
- Restarted your device (usually it works without, but it’s sometimes required)
- Turned on an app
- And then either:
- Selected its window
- Pressed ctrl+shift+i
- Gone to settings → About → Development options
- Scrolled to the relevant app, and clicked one of its windows under the fourth row “Windows”
And also, if you have followed all of these steps - does it work if you try it on the settings app (for the second approach you’ll need to tick “show built-in packages” in development options)?