I am sorry that there's only one image to go by, I was hoping that support was possible via something private like email/DMs, as I don't want to publicly show the model I have yet.

I don't know shit about rigging/weighting or really the basics about modeling, but I am trying to get a model I have into GMOD for a little shitpost video amongst friends. I've tried using Mixamo and Accurig for auto-rigging it beforehand, and both crash in the program when trying to compile using a .GLTF. The only thing that doesn't crash it is when I use an FBX version of the model that was auto-rigged with Mixamo.

Everything looks normal in the program itself, the skeleton, textures, etc, but when I try to use it in GMOD, it's stuck in a t-pose with this really weird textureless warping effect. I have no idea if this is a problem with the model itself or the conversion. 

FBX is quite buggy I'll admit which is why it's experimental, I don't know if updating the engine will fix it or not, but as for GLTF the crash seems like a bug most likely. I have an email listed on my website (which is amaxivermis[at]tuta[dot]io) so you can reach out to me there

Just a reminder on the email if you're still working on the problem! No worries if you fixed it yourself or changed your mind