Thank you for sharing this video. After attaching the meshes, go to the right panel and set Location and rotation to 0,0,0 for Torso, Legs, Face and Feet. Sometimes the names will change to SkeletalMesh1, Skeletalmesh2 etc, it’s annoying but it can happen, but you have to rename them back to the original names in order to LODSynch component work properly. Also, if the meshes disappear, just save and close the blueprint. The meshes will be there.
