ANSWER:

The extension works for me only if the address bar isn’t focused in Chrome.

Additionally, I had to perform some manual tweaking of system shortcuts.

It seems that these keyboard shortcuts are also assigned by default to virtual desktops that don’t exist at the time of you pressing the shortcut.

So you need to first add a ton of additional desktops to Mission Control, then unassign their CtrlNumber shortcuts, and then (optionally) remove those desktops from Mission Control again.

This is what I did, and starting then, Ctrl1 to Ctrl6 worked for me.

by Daniel Beck from http://superuser.com/questions/427134