While in the process of making custom themes for zorin (and essentially gnome), I came across an unexpected crash of zorin-appearance. I have been unable to start the window due to the error:
(zorin-appearance:2278): Gtk-WARNING **: 23:23:33.564: Could not load a pixbuf from icon theme.
This may indicate that pixbuf loaders or the mime database could not be found.
Gtk:ERROR:../../../../gtk/gtkiconhelper.c:494:ensure_surface_for_gicon: assertion failed (error == NULL): Failed to load /usr/share/icons/Causality-Dark/mimetypes/16/image.svg: Unrecognised image file format (gdk-pixbuf-error-quark, 3)
Documentation on Zorin Appearance is very limited, meaning I don't have a way to fix it manually without scouring my system for the config / cache files.