In VisualEditor start a new line, switch to italics with Ctrl-I, enter some text, and leave italics mode with Ctrl-I. At this point, the Cursor-left arrow key won't work. The same is true for Ctrl-B (bold text).
Another instance of the same bug: start a new line, enter the text "ab", hit the cursor-left key to place the cursor between the 'a" and the "b", then hit Ctrl-I and insert some italics text between the 'a" and the "b". At this point, the left- and right- cursor keys can be used to move the cursor within the inserted italics text only, but they can not be used to move the cursor before the 'a" or after the "b"