Dlc with steam how to unsubscribe n resubscribe to items from inventory. You have always been able to but can't do it now. screen shots show. you can't do it from properties either.
Known issue, Steam has recently screwed the pooch, Marcel has posted in the steam developers forum, workaround is to delete from the installed/location-installed/vehicles section and from …steam/steamapps/workshop/content/365960/car/track folder and let the game regen.