I see this on newer KDE Plasma Version 5.8.5 on "KDE neon 5.8" and on Plasma Version 5.8.5 on "Fedora 25". On Fedora 23 with KDE Plasma Version 5.7.5 the comic icons are present as expected. All systems are running the same set of comic plugins in ~/.local/shared/plasma/comics/. (I don't see a configuration setting that enables or disables display of these icons.)
This got fixed.