Smart guides not working on a particular document!

This is a weird one. All of a sudden, Smart Guides stopped working on a job Im doing. They were working but they just stopped. If I create a new blank document, they work fine but switch back to the old document and they dont work. Ive turned them on and off, saved and quit, rebooted the mac etc etc but they just wont work on this document. Ive even cut and pasted everything onto a new document but they still dont work.

Can anyone help please - I really need them for this job and cant get them to work!