I'm not quite sure what's going wrong with them either, I believe it's a problem with the .phy files for the characters

I might be a little late for the party here, but I may have found a workaround for your model problem. When you got to spawn one of the models that doesn't work, right click on the model and pick "spawn with creator tool" or something along those lines.

You should be able to spawn a model after a few tries. It's never worked on the first shot with the tool, but the third to fourth have always been successful.

Note that there's a few other bugs, such as being unable to use other tools on them, but at the very least, you have your model that you can move and pose with the physgun.

Hope this helps!