I don't know much but my pal's got a steam dedicated server and i had kind of the same issue but with a couple more mods i was trying to install. A friend showed me how to start the server from the "start_headless_server" file found when you right click the dedicated server in steam then hit "manage" then "browse local files" it should be below all the folders. hope this is a viable work around for you as it was/is for me!
