I have tried to turn off the sleep setting on two of my fire stick 4K devices. One worked fine, the other returns null for the screen_off_timeout before and after I ran the put command. I am setting both settings now.
Thanks for the reply. I have three fire 4K sticks. One comes back on to the “are you still watching this”, when I select “yes” it goes back to the app I was on, displays old content for a few seconds, and then start the current TV show. I think that is better! The other 2 turn on to the home screen. The one in particular, the two settings are saved correctly.
mantis:/ $ settings get system screen_off_timeout
mantis:/ $ settings get secure sleep_timeout