There is definitely something going on with the plant/soil chemistry here that isn't normal. Years ago, when I was still a teenager, I ran into this. Plant didn't show any obvious signs of anything being wrong, foliage was green, no visual cues whatsoever. It was just flat out dormant. I never did get to the bottom of what the issue was, but I know it wasn't the genetics, as they were premium beans, jack herer crossed with something.
My gut tells me there's a nutrient lockout due to an unfavorable pH. My reasoning is...with the growth stunted to such an extent, there's no need for the plant to use what it already has available to it. Thing is, you might be tempted to kind of sweep her under the rug, but unless you diagnose that plant, you are putting it in the hands of chance and chance alone when it comes to future grows. You really want to figure out what's going on here, it's in your best interest.
If for some reason you just can't, or refuse to get a pH pen to probe the cause, add some dolomite lime (or some other amendment that has about a 7.0pH) to the topsoil and flush it with a bunch of distilled water to try and neutralize the pH of the soil. Then give her a week and see what she does. If you see positive results you know for sure the pH was either too high or too low. Keep in mind, it takes a lot of water to bring pH levels back to where they need to be, and it isn't something that should be adjusted too much at one time. If you had a pH pen, or even test strips, you would know if you needed to go up or down.
Another thing you might try, in combination with the above mentioned, is transplant to a pot of the same size, only add 20-30% perlite to the mix to provide for better aeration of the soil. The roots may be struggling to really thrive the way they need to if your soil is too compacted.