Halo 3 achievements or completion aint registering

I have done Halo 3 Campaign on legendary but when I go to halo waypoint to see that I’ve done it, it says I have not started Halo 3 at all. no achievements, nothing.

I have the same problem… i played CE anniversary offline but then i logged in to XBL an the game or XBL didn’t recognize that i reached some achievements… could anybody help me!?