Glad you got it sorted out Delta.
Do you know of any good guides for working with Source2 models?

Yeah, sorry, I did read that in your post, it just went bloop when I was replying from memory and that better FBX importer/Export was on Blender market not Gumroad.

But, looking through the features of the exporter I mentioned I see this in the features but I'm not sure if this is what you want...

Supports multiple vertex color sets.

It's $25 bucks but if it supports what you need and you're going to be doing this over time, it might be a good investment. (Personally I'm not at that level yet and I have Akeystu 2020 if I want to get into FBX animations.)

Link is here if you want to check it out:

https://blendermarket.com/products/better-fbx-importer--exporter

Sorry Delta, I'm still working with Source and GoldSrc models, I haven't stepped into the realm of Source2 yet but that was all I could think of coming out of Blender. Are there option in the importer for the modeldoc files or maybe in the FBX exporter? The Blender FBX exporter is pretty limited but there is a"Commerical" importer/exporter for blender on Gumroad that has been enhanced and supposedly works much better.

Are you applying the transforms before exporting?

Artfunkel,
I've pulled this Bus to have a look at it and I have managed to export it.

The Context error is happening on instanced objects. There are 2 sets of passenger seats that are instanced, when exporting Blender crashed when trying to export them.

Also, this bus is fully rigged with a lot of shape key drivers, controlling various aspects of the armature to textures and emissions and mesh to adding Subsurf and bevel modifiers.

One shape key actually switches the entire bus from right hand drive (British/Japan) to left hand (North American).

Because of the way the model is pinned together using Empties, origin points are all over the map.

And the poles inside the bus are still Bezier curve that need to be converted to mesh before exporting.

Its really a well done model.

https://i.imgur.com/bAdYnoi.png

Edit: One other point I forgot to mention is that not everything is Unwrapped.

Vertex groups are not shapekeys, they have no affect on a VTA. Vertex can have a _ in the name.

Are you exporting SMD or DMX format objects?

Go to the object in Blender, Look at the Shapekeys, if only it has only a basis shape, delete the shapekey, re-export the object and recompile.
OR
If the object has multiple shapekeys, make sure the ones that are to be used (have flexes) do not have a _ in the shapekey name. A _ in the name of a shapekey indicates it is a corrective shape. These are written to the export but StudioMDL does not recognize these as usable flexes.

6 armatures, 281 Mesh objects, 61 materials, Curves that need to be converted to mesh objects, Subdivision-subsurface modifiers, edge split modifiers, 128K + verts before the modifiers are applied, Drivers and shapekeys up the ying-yang. No wonder your having a problem compiling this thing.

StudioMdl can't handle something as complex as this, it has to be simplified to the extreme before it will compile. Materials alone are double the allowed amount of 32 mats.

yeah, I have had this problem as well.
Try this...
Go into the Renders Property panel,
Find Performance,
Toggle the High Quality Normals Check Box from what it is now. (if it's off, toggle it on)

See if that fixes the problem. (You may have to do this for every mesh Object, I forget if it's a global setting)

Because the normals of the invisible areas are reversed. The mesh front faces are pointed into the model and need to be flipped to point outward. This is usually caused by split models where Blender can't determine which way is inward and which way is outward and depends on how the mesh was built. Another cause is by using a scale x type command that causes stuff on one side of the mesh to be flipped to the other side. A lot of ppl don't realize that this method also flips normals.