This seems to be a very old bug, which was already reported here: https://bugs.kde.org/show_bug.cgi?id=114297 but I though I'd better create a new report, who knows, whether the old bug is still monitored (the CC list is not very long).

This bug is about using SMB shares in Dolphin. When viewing the shares in detailed view and clicking the little arrow in front of a workgroup or computer name for expanding the view, the contents are displayed on the same level and not as child nodes. This is very confusing (especially because they're ordered alphabetically together with the parent nodes) and should be fixed.