UE5.7 MetaHuman uses facial texture maps; how to resolve missing textures when creating a character?

Create a digital human character, using a facial model template, and add facial textures with Texture Overrides. They display normally in the editor, but after using Download Texture Sources, the facial materials are missing. Can anyone help explain the reason? Thank you very much!

Virtual textures perhaps? You might want to disable them in project settings and see if it resolves this.