Another data point:
My 2014 Leaf SV, 45k miles, developed this clicking when accelerating and slowing about 2 months ago. Temps are warming up a bit here in OR so driving around with windows down proved too much clicking to be heard! Called Kiefer Nissan in Corvallis. Scheduled an appointment.
Short version (4 1/2 hours later, they also updated two unrelated software things): Axle nut(s) on both front axles were loose. NEW torque spec fixed my clicking. Tech told me the new spec (200 Nm, 147 ft-lbs) is needed for ALL Nissans with these same axles (Leaf, Juke, Sentra). old spec (125 Nm, 92 ft-lbs) allows for too much play and eventually the clicking ensues. 120 buck diagnose fee reduced to $60 labor only. I am pretty happy. They did a great job explaining.
Hope this helps. Ask any questions you may have.
I did the best homework I could thru the interwebs and put together a word doc to show the service person and tech person. TSB ntb12-055 did not apply to my VIN range. peculiar but I guess not unheard of to have similar problem traits as others, yet not be included in a service bulletin. No grease was used.
We shall see how this works long term and will try to re-post in a few months. Thanks to all who support and post to this great forum!