IF you are on your watchlist page, and you are being told you don't have that profile on your watchlist, that is a statement of fact.
Also, it seems as though Find & Search is limited to searching your watchlist. At least so it tested out for me.
So your best bet then is to do as Dennis suggests, in order to locate any profile not on your watchlist
You see the URL in the address bar of your own profile? https://www.wikitree.com/wiki/Weldon-647
Change the "Weldon-647" to "Jones-345677", so it reads https://www.wikitree.com/wiki/Jones-345677
although, since this is a made-up number, it will only take you to a "Page Not Found" page.
Try my own ID, so it reads https://www.wikitree.com/wiki/Haywood-41