To reproduce problem create several (7-8) site templates, then go to Sites and press "Add" button.
Near to "Add" we will see popup with list of site-templates. Problem is - only part of site templates is displayed. To see others user should scroll this list down. But there are no any scrolls (scroll displayed only then user started to scroll) or any other sign showed user what there are more items in the list.
Problem reproduced for any other "Add" buttons then popup with list is displayed after it (for example create web-content from structure - see second screenshot).