From https://bugs.launchpad.net/catfish-search/+bug/1476358 The default Thunar 'Search' custom action does not work in Linux Mint Xfce 17.2. The default command used is catfish --fileman=thunar --path=%f (also recommended here: http://docs.xfce.org/xfce/thunar/custom-actions). But in fact it doesn't work. It does nothing. It works by replacing the above command with: catfish --path=%f
The "--fileman" flag is no longer supported. The other issues documented in this report are resolved in git and will be included in 1.4.6.