I had some minor issues with portal 2 as well but trying windowed, hook helpers and alt hooking eventually got it to work, Ive played games like g-string that is based oh source engine too it all works eventually.
But trying hl2 mods as mods, that are not standalone games just refuses to hook no matter what.
Specifically in question are smod (including standalone, which is still using hl mod structure to run, not like portal 2 or gstring or dark messiah which all work) and mmod, none of those worked no matter what combination of things I have tried, even launching hl2.exe directly with parameters to start a mod didnt hook. Launching same hl2.exe vanilla hooks and works in 3d.
Every successful source game that I have tried has vorpx hook from start, when into videos appear, with mods that refuse to work hooking message appears only in main menu and fails eventually.