The console is not partial backup aware. We are having discussions on what we may add to the next release. In the meantime, you'll need to restore from script on that database. For example:
exec master..xp_backup_database @database='p', @filename='c:\olr\p_full.bkp'
exec master..xp_backup_database @database='p', @filename='c:\olr\p_partial.bkp', @read_write_filegroups=1
exec master..xp_backup_database @database='p', @filename='c:\olr\p_partial_diff.bkp', @read_write_filegroups=1, @with='differential'
drop database p
exec master..xp_restore_database @filename='c:\olr\p_full.bkp', @with='norecovery'
exec master..xp_restore_database @filename='c:\olr\p_partial.bkp', @with='norecovery'
exec master..xp_restore_database @filename='c:\olr\p_partial_diff.bkp', @with='recovery'
Thanks.