I fixed this bug in my machine just editing the /usr/share/applications/gnome-online-accounts-panel.desktop file adding Unity in the OnlyShowIn property. It was configured only with GNOME, see the configuration before and after bellow:
Before OnlyShowIn=GNOME;
After OnlyShowIn=GNOME;Unity;
I fixed this bug in my machine just editing the /usr/share/ applications/ gnome-online- accounts- panel.desktop file adding Unity in the OnlyShowIn property. It was configured only with GNOME, see the configuration before and after bellow:
Before
OnlyShowIn=GNOME;
After GNOME;Unity;
OnlyShowIn=