When you have Dolphin open and also the terminal option open changing tabs changes the terminal directory to match, awesome, but one small problem is if you are currently viewing a tab and have another tab open then decide to close the tab you are currently viewing it does not update the terminal directory. On ubuntu 16.04 with backports ppa. https://community.kde.org/Kubuntu/PPAs
Thanks for the bug! I just tested with Dolphin compiled from current git master and this works properly with your steps to reproduce.