The Workshop places files it knows about in the addons/workshop folder and they must stay in that folder for the Workshop integration to work properly. Please DO NOT copy your add-ons around in this fashion. While this will appear to work, you'll break those mods for future updates and will cause duplications to occur when the mods come back online.
Originally posted by Paz:Yeah the workshops broken again, i have exactly the same problem only way around it is to move your addons out of workshop folder ' steamapps\common\left 4 dead 2\left4dead2\addons\workshop ' and into original addons folder ' steamapps\common\left 4 dead 2\left4dead2\addons ' this will allow you to use any addons you have downloaded already but you wont be able to download new addons until after the workshop is fixed.