I've finally managed to look into this. I've made my own scene which imitates the motions of your screenshots in a very simple manner and everything exports correctly.

Can you upload your blend file for me?[pasteall.org] There may be a complication I don't currently know about.

You only want the io_scene_valvesource folder.

I'm not going to be making proper downloads until 2.80 ships precisely to discourage people from using an unstable version of the addon with an unstable version of Blender. If you're having trouble installing please stick to 2.79 for now.

StudioMdl will automatically triangulate DMX meshes on compile, perhaps something is going wrong there? Try triangulating your mesh then exporting it to DMX.

This is a bug in Blender, you should report it to them.

2.80 isn't ready for general use yet, and neither is the new version of the addon. If you don't know what you are doing use 2.79 instead.

You either didn't apply scale to the armature, or you didn't export everything that uses the armature (reference meshes AND animations) after applying scale.

Not yet, I have a reminder to look at it soon though.

Get a newer build of 2.80

Still no crashes here with either version of Blender. In any case, it's definitely not an issue with the exporter!

Fixed, get the latest git change. Anyone using an older version of 2.80 will need to update.