Could it be, that xfce4-terminal uses a legacy icon name for terminal icons ? I ask because I just switched to what will become Fedora 30 (soon) and I noticed, that the gnome icons package has put a few icons into a new subfolder called legacy. Amongst these icons is also the terminal icon. Therefore my guess here is, if xfce4-terminal is using a legacy name for the icons it needs ? May I ask you if you could verify my theory ?
What icons have been put to "legacy"? By default, xfce4-terminal is using the "utilities-terminal" icon: https://git.xfce.org/apps/xfce4-terminal/tree/terminal/main.c#n326 You can make it use another icon by providing the icon name via -I/--icon parameter.
Reporting back: https://bugzilla.redhat.com/show_bug.cgi?id=1669152 Looks like it's a packaging issue with upcoming Fedora 30.
Thanks for the update! Can we close this bug then?
Yep, go for it.