Graphical Wireless scanning

I am able to connect to a Wireless network using the graphical interface of Ubuntu 16.04 (Unity) by manually configuring a network whose name I know.

I can also scan for networks and their information using the terminal command sudo iwlist scanning | less and this works just fine. But there used to be a nice graphical way to look at available wireless networks, just by opening the drop-down menu in the upper right corner of the screen. Even when I am connected to a wireless network, I no longer see any networks (or signal strengths) in this drop-down menu. What could have happened? I am working on a Dell XPS 13 laptop, the Wifi is Intel Wireless 8260, the kernel version is 4.4.0.

EDIT: It would seem that this problem sometimes appears and disappears after rebooting or connecting/disconnecting with certain networks. JPS' solution provides a temporary workaround, but problem comes back once in a while. I will try to figure out what exactly triggers the problem, but sometimes it is just there when the computer boots up.