Here is a collection of known issues with Wall Worm, 3ds Max and/or the Source Game Engine.
The Wall Worm Material Library Generator originally created DirectX Materials for all materials. But updates to the VMF Exporter changed the way materials are interpretted. Whenever possible, you should not use DirectX Materials.
Fixed in WWMT 1.772
The orientation of models in the QC Generator has been flipped on the Z-axis and the VMF Exporter is also rotated to accomodate this result. You may need to recompile models compiled before the 1.772 update.
Fixed in VMF Exporter 1.21 (WWMT 1.768)
The current VMF Exporter does not yet export the correct texture alignment, rotation and scaling on brush geometry and displacements.