For some time now, everything in Garry's Mod has been like this.
I tried asking the Steam Community page but apparently nobody believed me there and just said they didn't have the problem.
I have almost every source engine game, so I know I have the content, it's just that Garry's Mod refuses to work with it. I tried updating everything, but I suspect something related to Steampipe is the issue, because I never had these problems beforehand. I've played this with my onboard graphics and my video card, so i doubt that's an issue either. Am I going to have to reinstall all my source games? I already did it to garrys mod to no avail.