Can't SHOW GRANTS after MySQL re-install
Entries existing in the mysql.user table and privileges being recognized by the MySQL server are two different things that are only loosely-coupled. 

mysql&gt; FLUSH PRIVILEGES;


Any time you change the content of the mysql.user table, other than by issuing a GRANT ...-type statement, including restoring from a backup, you need to issue the FLUSH PRIVILEGES command before MySQL will realize those changes have happened.  This should make the users visible.  

Or, by now you may have restarted the server, which would also fix it.