I've discovered a bug after upgrading to 5.0.1 (400591). When attempting to create a child tag by dragging and dropping an existing tag onto another in the tag view the resulting child tag disappears. The tag still exists in the program and is searchable, but does not appear in any of the tag lists (tag view or tag tree in side bar). If you search for the tag in tag view it simply highlights the parent tag, but you cannot select the child tag. After restarting Evernote the child tag reappears, but obviously there is a bug in the code where it refreshes the tag lists.