For all glitches and issues with the asset downloader, it'd be helpful to get problems reported here:
https://github.com/makehumancommunity/c ... oad/issuesObviously most assets should download properly. However, there are examples where a mistake inside an asset descriptor (MHMAT, MHCLO...) will prevent it from working properly after download. One example is when the author of an asset has uploaded it with absolute paths ("diffuseTexture = c:\users\myusername\documents\makehuman\v1\data\clothes\myasset\diffuse.png") inside the asset file, rather than relative paths ("diffuseTexture = diffuse.png").
The third party materials not working for core assets problem is known, and it is on the roadmap to be fixed before a stable release.