have a dozen of ZIP archives in a single folder, each containing a file with a different name. Select them all, right click and launch the "extract here" action. Only a random number of archives are unzipped. This is particuarly nasty considering that unzip *.zip doesn't work..... so I can't see any workaround that doesn't include a 10-lines long script -_-
You should file this at bugs.kde.org so it gets fixed upstream.
see above comment.