Workers are having to be prompted to restart working even after the offending barb camp has been destroyed, it happens time and time again and will last for the continuation of what ever is being built, upon moving to the hex next door the same is happening. It seems to me that the workers are not recognizing that the barb camp/camps has been destroyed and will continue to need prompting for the duration of the game. When playing wide empire games this becomes extremely time consuming. EDIT I have just started another game and the problem seems to be with City States and other Nations that we were once at war with, our workers don't seem to recognise that we are now at peace! I have discovered that if I go back to war and conquer the offending City then the workers go back to work as normal.