Close button does not have tooltip on all create an item page

Steps to reproduce:

1. Log in to back office.
2. Go to Content / Content structure.
3. Create a new item e.g. Folder.
4. Verify if 'Close' button at the upper left side of the page has tooltip.

Actual result:

See attachment.

Close button do not have tooltip.

Expected result:

Close button should contains tooltip information.

Comment:

The problem exist on all create an item page (Article, Folder, Forms, File, Image, User, User group).