That poor girl looks like she doesn't have enough root structure to support her.

Over watering will lead to suffocation of the roots and eventual rotting.... Once the roots are dead there's nothing to feed leaves,... so leaves start dying.... It's a vicious cycle, and if you don't balance it right on the razor's edge your going to get cut. (pardon the pun)

Too dry and the new roots will die,... too wet and the rotting will progress.

I've found the MG soils to be somewhat difficult to control moisture content.

Good luck with your girl, but I wouldn't expect much given her sad state in that pic.