You should check your SNAP and GEO settings which can be accessed in the lower right hand corner of the screen. Next to the xyz coordinates you'll find the two buttons that say SNAP and GEO. If either of these are greyed out their respective option is turned off. You can also right click on either to get a more detailed "Drawing Aids" window where you can set your snap and "geo"lines settings.
I hope this addresses the functionality you're talking about.