ok i am not on SteamOS, rather on Bazzite, but the problem is the same... i cannot get mods to work. i am using the flatpak version of VS so mods are in the same directory, but if i place mods in there (in zip format) they don't show up when i boot up the game. i had the exact same issue on Linux Mint also, so this has to be a flatpak issue? please help me with this :)