Installing Gnome extensions support and the system-monitor extension - https://extensions.gnome.org/extension/120/system-monitor/ - was the solution for me.
In case you also, like me, were not familiar with the gnome extensions, please follow these steps:
- Install add-on for your web browser:
For Google Chrome, Chromium, and Vivaldi, install the add-on via chrome web store. That's what I have done, but there are also add-on for other browsers: For Firefox, install add-on from Mozilla Addons site.
For Opera, install it from Opera Addons site.
Open terminal either via Ctrl+Alt+T, or by searching “terminal” from app launcher. When it opens, run the command to make it work in Chrome:
sudo apt install chrome-gnome-shell
The system-monitor extension has some requirements - run the following command on the terminal:
sudo apt-get install gir1.2-gtop-2.0 gir1.2-networkmanager-1.0 gir1.2-clutter-1.0
Finally go to extensions.gnome.org via your browser (I have used Chrome), install any Gnome Shell Extension by turning on the switch on the web. For the system-monitor extension, the link is https://extensions.gnome.org/extension/120/system-monitor/.
After upgrading to Ubuntu 17.10 I also had this problem and I was missing the indicator-multiload features. I now like this system-monitor extension even more - it looks better, has relevant information, it is easier to configure and it is easy to find and install, at least when you get into the gnome extensions.