TOPIC: Some skins are invisible to me

I know you've probably gotten this question before, but is there a way to fix the bug where some playermodels/skins are invisible? I've tried restarting the game and the computer and redownloading the addons, but it hasn't worked.
I also have CSS, HL2 and the episodes and all.

I've seen Users experience this issue before, and not only on TTT, I'm rather curious as to how to resolve such a problem.

Downloading the content and restarting the game always fixed this for me