Cannot assign available Acrobat Pro license to user

My company has 6 Acrobat Pro licenses. 5 are used. I want to assign the last license to an employee. When I go to user/product/edit product/select product, Acrobat Pro is there, and it shows (1) available license. I click the box (at which point, teh available license goes to (0), and click save. See attached screenshot.  I get a green pop-up box that says "1 user updated".  But the license is not assigned to the user, and there is still one license available.

Can anyone help?