The problem now is that you put the .ace files in a folder inside the Textures folder. They have to be put directly into the Textures folder. It'll then work, as long as the Textures folder is directly below the folder containing the .igs file (which it is).
In other words, the Blueprint Editor looks for a Textures folder wherever the igs file is located (the scenery blueprint xml file tells it where the igs is), and it expects the .ace files to be in that Textures folder.