I had to redownload the Korean VO early today after the update and when I logged in some sounds were missing (like skill sounds, dash and some others). I went to the game folder and saw that the voice pack for some reason got downloaded in this folder:
steamapps\common\Lost Ark\ client\EFGame\ReleasePC\WwiseAudio\Korean
and I know that the audio files go on this folder
So after moving the Korean folder from the first path to the second I got my sounds back. Just posting here in case that happens to someone else and maybe it is a bug that the files are being downloaded in that location.