If an item in the context menu is a group-item, the sub menu may not trigger when 'mouseenter'-ing the item from outside the context menu. This is most noticeable when the first menu item is a group-item. It appears the menu item 'mouseenter' event is not triggering. If the cursor is already in the context menu (ie when the group-item is second in the list for instance) the event triggers as expected.
Root cause of the issue is that when the context menu is hidden, sub menu's are hidden instead of removed. So the sub menu works correctly on the first attempt but any subsequent attempts will fail because the sub menu is already part of the DOM. Proper removal will allow the sub menu to be created correctly.