Snapchat has a safety feature that prevents immediate re-blocking or re-adding in some cases. If you just unblocked them, the servers may need time to update. Wait 24 hours and try searching for them again.
: Unblocking and re-adding a user does not restore your previous chat history, saved messages, or Snap streaks; these are permanently deleted upon the initial block. how to find someone you unblocked on snapchat
After unblocking:
If searching directly isn't working, you can try the dedicated menu. Snapchat has a safety feature that prevents immediate
Go to the (magnifying glass) at the top of the main screen. Type in the person's exact username . : Unblocking and re-adding a user does not
If you cannot remember the username, Snapchat may suggest the person through mutual connections or your phone's contact list: How To Unblock Someone On Snapchat - Step By Step