When you click the button "Select none", it does the same as the "Select all visible" button, putting all the items selected.

Steps to reproduce

tc-332

Setup - Create some content

Log in as admin in admin
Click "Content structure" in top menu
Create new folder "Folder 1"
Create new folder "Folder 2"
Create new folder "Folder 3"
Create new folder "Folder 4"

Test "Select all" when none are pre-selected

Click "Select" button, then "Select all visible"
Validate that all folders are selected

Test "Select all" when all items are already pre-selected

Click "Select" button, then "Select all visible"
Validate that all folders are still selected

Test "Select all" when some items are already pre-selected

Uncheck the check box for "Folder 1", "Folder 3"
Click "Select" button, then "Select all visible"
Validate that all folders are selected, including "Folder 1" and "Folder 3"

Test "Select none " when all items are alread pre-selected

Click "Select" button, then "Select none"
Validate that all folders are deselected

Test "Select none" when none are pre-selected

Click "Select" button, then "Select none"
Validate that all folders are still deselected