After running into Oauth2 issues with the Thunderbird snap revision 288 (v102.7.0-1) I tried reverting to the previous revision 287 (v102.6.1-1). While the reversion worked and thunderbird starts, it no longer shows any window controls and attachment icons. The following messages are shown during startup suggesting that there is an issue loading icons from the icon theme.
(thunderbird:248123): Gtk-WARNING **: 11:47:09.407: Could not load a pixbuf from icon theme.
This may indicate that pixbuf loaders or the mime database could not be found.
[Parent 248123, Main Thread] WARNING: gdk_cairo_surface_create_from_pixbuf: assertion 'GDK_IS_PIXBUF (pixbuf)' failed: 'glib warning', file /builds/worker/checkouts/gecko/toolkit/xre/nsSigHandlers.cpp:167
(thunderbird:248123): Gdk-CRITICAL **: 11:47:09.407: gdk_cairo_surface_create_from_pixbuf: assertion 'GDK_IS_PIXBUF (pixbuf)' failed
[Parent 248123, Main Thread] WARNING: g_object_unref: assertion 'G_IS_OBJECT (object)' failed: 'glib warning', file /builds/worker/checkouts/gecko/toolkit/xre/nsSigHandlers.cpp:167
I’ve tried to disconnect and reconnect the icon theme but that did not solve the issue. Any suggestions on how to get the icon theme to load properly after reverting?