The page tree pagination doesn't work when editing a template provider

To reproduce:

• make sure you have a long document tree in the wiki (e.g. activate the display of hidden pages for the current user)
• go to the administration, to the template providers section
• create a new template provider - select name (and space), and click create
• in the form to fill in details of the template provider, the tree displayed for "List of locations where the template must be available" will display some entries and then the "X more..." link (in my case, 16 more, see screenshot)
• click on this link (16 more), to unpack the rest of the tree

expected result

• the rest of the tree is unpacked (16 more entries) so that I can select another parent (e.g. Sandbox)

actual result

• only one entry more is added instead of "16 more...", "Home", which is checked. There is no way to see the other 15 entries that the tree announces (see the screenshot)