SLH Mutant clone refuses to flower

Tech. Stuff
Strain-Green House Seeds Super Lemon Haze Feminized
Light-400W HPS (MH during 3 week veg.) veg'd for 3 wks. except mother that had 6
Soil-Happy Frog with 1/2 cup dolomitic lime for pH buffer
Veg Ferts.-Flora Nova 7-4-1, Generic Fish emulsion 5-1-1 both applied bi-weekly
Flower Ferts.-Earth Juice 0-3-1 currently applied once (due next week)
pH-dialed in at 6.6-6.8 for ferts. 7.0 for water only
Ventilation-Continous with osc. 8" fan

1st pic is of the mother, 2nd is the oddball. The other 2 clones are flowering nicely. All the plants are rotated daily to make use of the "sweet spots" of the 400w HPS. The plant in question also has some kind of weirdness going on with the stem as it is only 3/8" in diameter at the base but, at 14" up, the stem distorts and flattens out to over 5/8" wide and about 1/4" thick. The top leaves are also distorted and "whorled" and show no signs of going into flower despite being genetically identical to the others. I am considering throwing it into a 36 hr. dark period as I understand there is zero benefit in triggering beyond that. Anyone have a similar experience or know what might be going on with this thing? I should be able to post a few better pics of the growth pattern later when lights are due but cell phone is not the best at images.

how long you have it in 12/12...didn't see that info in your post... 36hrs dark might help, but it might just need more time...if it's only been a few days I'd just wait at least a week.,,,, are you not even seeing preflowers?

Starting the 3rd week of 12/12 yesterday. Again, the others along with the mother and 2 "Cheese" plants are all flowering quite well but this one is stubborn. Has to be a stress factor that I didn't identify on that one plant but damned if I know what it is. Pre-flowers were showing prior to 12/12 just like the others. I am sure that it will eventually flower but just puzzled as to why. For all I know the leaf-deformation could be a good thing.

wow no idea...I was expecting you to say like 3-5 days, but that's way too long...I'd say go for the 36 hr dark...It's not going to really hurt anything, and other than the no flowering, the plant looks healthy...I'm stumped.

The mutant has finally started to flower. I kept it in the standard 12/12 photoperiod hoping it would sort itself out and it appears to be doing fine. The pattern or arrangement of the flowers looks a little strange. I hope that it continues this growth pattern throughout its developement. I have no expectation of it producing any kind of "superbud" or unusually high potency, I simply enjoy the weirdness of it.

This is why I chuck those mutant looking ones out, lol. You just never know.