While building with the slab tool, a number of the ladders and scaffolding was not removed and i was unable to remove them also workers kept going up to them and trying to remove them continuously with no success.
If you would like a video of it let me know.
Hello, @cro5point 
Yes, definitely a screenshot or video would be helpful to determine the building shapes that are troublesome!
will do when i get home
Ok so it seems to have fixed it self, the first thing that happens when i load the game is the workers finished removing the supports structures. Its very strange as i had restarted a number of times before posting my bug report.
Hmm maybe the AI was stuck 