This is on purpose. You can't noclip through the world, nor can you noclip through other player's props. This is to prevent people from noclipping into other players' bases and killing them.
A link to our steam content pack is located right above this very FAQ. After subscribing to all of the addons, restart your Garry's Mod. If you still have errors, it is very likely you do not have some games mounted in your Garry's Mod. (CS:S, TF2...)
Report it to an administrator immediately. Script errors are uncommon, and are most likely the cause of a broken workshop addon, which are largely out of our control. Report it on our Discord for the quickest fix.