Frankenmesh Issue

Both mesh groups in your .blend have the same cut number. Studio can only import one mesh group per cut number. If the item you're trying to overwrite with this .blend has multiple mesh groups, only one of them (the one with the same cut number that your meshes have) will be replaced with your mesh. Your .blend mesh set up needs to be the same as the mesh set up of the original LOD you're replacing. For each mesh group it has you need a mesh group and the mesh group you're using to replace each mesh group needs to have the same cut number as the mesh you want it to replace.