I've had this problem in 14.04 LTS and 16.04 LTS. After installing a new application (Viber, e.g.) via Gdebi, Synaptic or Ubuntu software, the application does not appear in Unity dash (or classic menu indicator) until I reboot.
It's quite annoying, is there an easy fix for this?
updatedb
command in terminal and then check to see if the app shows up.