I will take your word for it, I am clueless when it come to aquaponics.
With that said you know your set up.
A root issue could cause this, but I would think it would take more than crackin the tap root.
If you broke it very close to the stem that would cut off most of the root system.
I have broken the tips of them right off and the plant just slowed growth until the root system recovered.
So if you did break the tap root, it should not kill it.
I don’t remember having leaf issues, but I may have.
That very well could be the case here.
Hard to know really.
Your plant has this weird upward leaf curl thing going on on the upper left side.
Could that be to much light?
The other leaves edges are lifted upwards too.
Hard to diagnose things from a pic…LOL