I upgraded from 13.04 to 13.10 and now all icons in the application lens are gone.
This is what I tried so far:
apt-get install --reinstall unity-lens-applications
unity --replace
andunity --reset-icons
- moving
~/.config
to~/.config2
- deleting
~/.cache/software-center
and~/.cache/unity
Most of these things have been suggested in this question: Unity Applications lens is empty - but all to no avail.