I upgraded my Ubuntu 17.10 install to 18.04 yesterday, and I'm noticing that I don't have any AppIndicators anymore. Here's what I tried that didn't work:
Ubuntu AppIndicatorsin the gnome tweak tools
Ubuntu dockin the gnome tweak tools
- Installed the
KStatusNotifierItemgnome extension. It fixed the issue for a few minutes, then upon reboot the icons disappeared again and reinstalling it didn't work.