Rob,
Thanks for the reply. Here what I did:
In User info ->Search preferences -> search method: "Use system defaults" (no change)
Amp setup -> General -> Search Method: chaged from “Active + historical clients (exact match)”
to “Active + historical clients”, (also tried with "Active + historical clients + all categories")
Then I logged out, logged back in, but no help, same problem: empty when searched for nerh123440, but it worked if search for "nerh123440.btnrh.boystown.org"