I am developing a custom skill, and it is working very well in the simulator.
The Alexa app on my phone shows it as enabled, but it doesn't work on the device.
One of my utterances would be "Alexa, tell Desk Controls to light up my office desk". This works fine in the simulator, but on the device I get "Hmm I don't know that one" or similar.
The device is definitely signed in with the same account email etc as my developer account.