This three steps to make it work, as said in the comment 4:
1 - mv ~/.local/share/zeitgeist ~/.local/share/zeitgeist.bak
2 - kill -s TERM `pidof /usr/lib/unity-lens-applications/unity-applications-daemon`
3 - logout or restart Ubuntu
At the log back, the Dash goes again in search of applications.
This three steps to make it work, as said in the comment 4: share/zeitgeist ~/.local/ share/zeitgeist .bak unity-lens- applications/ unity-applicati ons-daemon`
1 - mv ~/.local/
2 - kill -s TERM `pidof /usr/lib/
3 - logout or restart Ubuntu
At the log back, the Dash goes again in search of applications.