@Pbas see my comment on XWIKI-18234. The content is organized in a hierarchy of nested pages. You have some top level pages like
Sandbox and then each page can have child pages. The
Sandbox page has by default 3 child pages and none of them start with “W”. So it’s normal that you don’t get any results when typing “Sandbox.W”. Create one and you’ll see it gets listed. The live table location filter works in the same way (check it on the Page Index). Moreover, the nested page tree doesn’t show any “WebHome” child page of Sandbox. This “WebHome” suffix in the page reference is a technical thing that we want to hide from the end users.