I have had this. Not positive, but its almost like the developing root system hits a pocket in the new medium that it doesn't like.
I found this, as I would buy soiless mix, then add stuff like worm castings and perlite and various stuff.
I would occassionally get a plant or two, that would do this, but only when young like your plant in the pic. I would grab the pot with both hands and flex/squeeze it, loosening the soil, semi breaking it up a bit. Leave plant in the pot, just loosen the soil in it.
A few days later, the plant would show a sign of some kind of new, normal growth. Of course it would be behind in stature of the others in the batch but often caught up (or close) during flowering.
My theory is the roots were packed too tight. Whether or not this was the case....dunno. But they all eventually came around.
Never had any plants do this when I ran hydro.....so draw a conclusion from that if you will too.
Also, try backing off on the watering as well. Too wet can make it stunt. Worse if done for too long, and early in a plants development.