So I was Working on my first map that is going to be a payload. I was working on it for weeks and everything was going well. But today, after the new update of TF2, the track props and some other props appeared as big red ERRORS, and when I tried to change the props in the model browser, the props don't even appear in the preview window. What do I have to do? I even tried reinstalling hammer and it's still the same. Please help me.