Hello Dactylicxx,
I have had the same problem as you. I think the problem could be due to the fact that your HE folder is not the root folder, but rather a subfolder on your C:\. I fixed this in the following way.
On my network share p:\HE\ i have a directory called Tree. So the path is P:\HE\Tree.
In that folder are the files for the tree. One tree.hgm, and one treetexture.dds.
In 3DS max, i apply the texture, from that folder. So, when you select your HERO Texture, you make sure you pick it from the P:\HE\Tree folder.
Then, in the repository browser, i upload those 2 files to the server, in the same folder there.
As soon as i then load the asset from the Library in the HeroEngine, the texture gets applied.
If you want to check whats going wrong, you could, in the HeroEngine, open the console window by going to the "windows" menu and then check "console". If there is an error with your texture, you will see it there.
If you got any more questions, just reply here.