I have missing icons for Slack and MailSpring (Electron based apps I believe) in Xubuntu 18.04 application switcher:
The application's icon appears correctly everywhere else (i.e. in panels, app launchers, etc.) - it is only the switcher that is not working.
I have tried solution from here with no luck: App icon not showing in switcher (alt+tab)
Any ideas would be greatly appreciated :)