Cannot create Loop cuts I have lost the ability to make loop cuts. When I press CTRL+R, nothing happens. I am not aware of any changes I'd made. It stopped working on BOTH my Macs, both running Sierra 10.12.5. 

I tried loading factory reset, using the default blender keyboard layout. When i type "loop" in the search box, it returns nothing. I've tried the new 2.79 RC, same issue.

Please help.
You can only add loop cuts in edit mode (which you can enter either by pressing TAB or by choosing it in a mode scroll menu at the bottom).