This bug may be linked to https://bugzilla.xfce.org/show_bug.cgi?id=14691 exo-icon-chooser doesn't display icons of the current icon theme that are symlinks. This happens both with svg and png. This used to work, at least in Xfce 4.10. To reproduce, you can search "inode-directory", which is often a symlink to folder.svg. It doesn't appear in the search results when creating a new desktop launcher for example. This makes it very hard to find the right icon as many themes have lots of symlinks. Thank you for your attention
*** This bug has been marked as a duplicate of bug 10126 ***