on my two Antergos (Arch Linux) Machines, i cannot see spotify in my taskbar/window list. However, it's visible in Alt-Tab-List.
1.) Issue is occuring on my ThinkPad X220 and my desktop computer (AMD FX4300, 16GB DDR3 RAM, 4TB HDD), both using Antergos Linux using Cinnamon 2.8.6 Desktop.
2.) I am using Spotify Premium (prepaid)
3.) I am using Spotify 188.8.131.52.gb8a7150f for Linux (installed from AUR (installs the offical .deb file + dependcities))
4.) When using spotify, it isn't listed in the taskbar/window switcher/window list. However, when pressing ALT-TAB, i can see spotify and switch to it's window. You can see the opened spotify window in the attatched Screenshot, and also it is not in the taskbar.
5.) Install Spotify on Antergos Cinnamon using yaourt -S spotify, start spotify.