Could be the solenoids. They open and close electronically to allow the fluid necessary to create the pressure needed during gear shifts. They open and close based on signals from the ECU/TCU telling it that it's time to shift. If the fluid is dirty (or otherwise they just failed) it could cause them to stick open or closed, and if stuck closed, the pressure of the fluid moving could push it open and then the fluid will rush in slightly late and cause what you feel as a hard shift. When operating properly, the Genesis trans drives like a Rolls where you barely feel any shifting. Creates luxurious drive.
Since you say it gets better after a battery reset, that could mean its electronics related rather than internal problems. The genesis has a feature that lets the car learn your driving habits and adjusts accordingly. Resetting the battery resets the learning and it will learn how you currently drive and probably shift better. I reset mine about once every month and it does tend to drive smoother after doing so. Another option is get the drain and fills done (I've had them done. Can still do drain and fills on a sealed unit, just really hard to do a flush if you dont have special equipment) and have the dealer reset the TCU learning (different from the ECU learning) and it will remap your shift points based on driving habits. Be mindful if you do this, it will take the car a few hours to adjust and shifting may be extremely rough at first while its learning. When they did mine, I left and second slipped like 400 rpm then slammed into gear (never happened before the reset), I immediately turned back to the dealer. Dealer told me drive it a few days and let it learn then come back if still no good. I did. After the 2nd day it started shifting much nicer. Fast forward several months and I'm still having issues, it didn't fix the problem, but it did help temporarily. I think it's all electronics related which keeps pointing to solenoids. Only thing that makes sense based on my knowledge of transmissions. Let us know how it works out
Hello I was wondering if you changed your solenoids, I’m having the same problem and think changing them is my only hope, and was wondering how you made out?