At some point, it does not show up on the menu bar.
It doesn’t show up even if I change the desktop settings, and others.
Then I found ‘pt-device-manager.service’ is running.
I probably installed related package some days ago while I was searching battery indicator.
Anyway, after disabling the service and rebooting, the indicator appears again.
I wrote this post for those anyone who suffers from the same symptoms,