Likely, go back to the start and define the IK bones in the original retargeting definition - yes you need to expand and add the specidic IK bones.
Also, its obviously only going to transfer over via retargeting if the IK bones are animated - if you are using Epic stuff, then the animations, as I’m sure you already know, do not animate the IK bones…
Still, I’m 99% sure you are entierly missing the step where you define the retargeting setup.
I think you so that in the new version by not selecting the automatic option.
Give that a try before abything else.