I found that ertan had the same problem and asked here for help. Not sure if that got resolved. I believe the “Status menu buttons” extensions somehow throws an exception and then is disabled by Gnome.
Rebooting restores the extension, locking it breaks it again. (I’m also adding this to the original post.)
The Error can be found through Gnome Looking Glas (Alt+F2 → lg), but I have no experience with debugging Gnome extensions.
Error: Argument ‘old_child’ (type interface) may not be null
I did try to follow your steps and
will reboot nowreboot, but it didn’t change anything.
sudo pacman -Syu sudo pacman -R gdm sudo pacman -Syu sudo pacman -S gdm sudo systemctl enable gdm sudo systemctl start gdm sudo pacman -Syu
Following https://forum.antergos.com/topic/3082/the-login-screen-for-antergos-is-incredibly-slow I replaced lightdm by gdm. Now my shutdown button is gone. (And more, I don’t remember what the other two did.) I can still shutdown with the command line.
Rebooting restores the button until I use the lock screen. It usually breaks in two steps, first both locking+preferences are available, and after the second locking only the preferences remain. (see screenshot)
Any ideas how to get back the missing buttons?