It looks like the developer option is correct, however I did not have that so I had to do some research. Apparently the last update made this option disappear. Select settings, scroll to "about phone" and click. "Build number" appears to be greyed out. Tap this 5 times and it will turn on debugging on your phone. This has repaired my flashing issue. I've been working on this for over a week, it's been a PITA! Hopefully this helps some other frustrated folks.
I know this post is quite old, but for those of you who haven't figured it out yet, go to settings, then below where "device" is written, press on "active display" its fairly straight forward from there, i hope this helped, and btw i'm using a moto x first gen, but i belive this should work on most android phones ; )