It seems that the version of Gnome 3.30 on Arch is so unstable with such poor plugin support (despite what the Gnome developers think, tray icons are still required, Gnome is not the only DE available) that I strongly recommend against using it for now. I’ve gone back to the comforting embrace of XFCE. Maybe when Fedora 29 is released 3.30 will be stable in other distributions.