Steps to reproduce issue:
1- Open a fresh character creator 3 project
2- Double click the 4K_CC3_Base_Female from the High Resolution of Essential skin and click Apply
3- Open the Export FBX and select Insta LOD, then select Merge Material (UV), select All.
For the Bake texture size you can select 4K or 8K.
For the Target tool preset select Unreal.
FBX options: Mesh
Finally click export and export the mesh.
4- Import the FBX file in unreal engine 4 (I used 4.24) you can use auto setup or without it doesn't matter.
Texture in the thigh looks like it's split in half with different details/resolution which is likely caused due to bad normal map.
Disabling the normal map seems to fix the issue but we lose the normal map of course.
Check the third image for the result here: https://imgur.com/a/PjeOALr
UVs of the material applied correctly and no skin defects.
Note: Base game character doesn't have this issue.
You can download the exported FBX with its materials here:https://1drv.ms/u/s