Hi Paizo!
I went searching for a particular user by putting their handle in the search field at the very top of the board, and then clicking the Users tab in the search results. I could not find the user, even though I verified that they were still around and I used the correct spelling. I actually copied and pasted the username in case it was a special character I wasn't picking up on.
I tested it with another user, and I could find them under the Users tab of the search results with no problem. After trying other searches, it seems like Users that are older (as in, the username is older, not the age of the actual person behind the username) still show up in the results, but newer Users do not.
If you're interested in the actual usernames that I tried that did or did not show up, feel free to send me a PM.
Thanks!