Really odd, the addon doesn't seem to contain any malicious lua code but it still screws up the ULX config.
These are all of the lua files it has:
1. slade.lua
player_manager.AddValidModel( "Deathstroke", "models/player/bobert/slade.mdl" ) list.Set( "PlayerOptionsModel", "Deathstroke", "models/player/bobert/slade.mdl" )
2. autorun/slade_npc.lua
local Category = "Deathstroke Injustice"
local NPC = { Name = "Deathstroke",
Class = "npc_citizen",
Model = "models/player/bobert/slade_npc.mdl",
Health = "150", KeyValues = { citizentype = 4 },
Category = Category } list.Set( "NPC", "npc_slade", NPC )
3. autorun/slade_player.lua
player_manager.AddValidModel( "Deathstroke", "models/player/bobert/slade.mdl" ) list.Set( "PlayerOptionsModel", "Deathstroke", "models/player/bobert/slade.mdl" )
The rest of the files are just materials and models (.vmt .vtf .vtx .mdl .phy .vvd are the extensions of them)
See anything in there that could be doing this?