What I do when I return to the starting "Unsourced" page is to refresh the page and voila, the entry there is removed ...
I don't know. I do know that if I type in my surname it yields a list prefaced as follows: This GARBER index was pre-built so it loads quickly. Click here for live data and advanced tools for collaboration, genetic genealogy, surname projects, etc.
Even though you don't get the message on the unsourced profiles index and I can imagine that something similar would happen.