imce_update_7001() never finish

Drupal 6.20 ->7.0 site
7001 - Removes {imce_files} in favor of {file_usage} never finish. Left if running for almost two hours but the only thing that happen is that is consume a lot of CPU. "drush updatedb" fails after a few minutes with:

Error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 260 bytes) in /Applications/drush/includes/context.inc, line 2254

Had a look into imce_files table but there is just a few files there:

SELECT * FROM `imce_files`
    -> ;
+-----+
| fid |
+-----+
|  17 | 
|  18 | 
|  19 | 
|  20 | 
| 118 | 
| 119 | 
| 120 | 
| 121 | 
+-----+
8 rows in set (0.00 sec)

Some quick debugging where I dump the result and break out of the upgrade:

  $result = db_query_range('SELECT i.fid FROM {imce_files} i INNER JOIN {file_managed} f ON i.fid = f.fid WHERE i.fid > :fid ORDER BY i.fid', 0, $limit, array(':fid' => $sandbox['last_fid_processed']))->fetchAll();
  var_dump($result);
  return;

But it returns a empty array:
array(0) {
}
Attaching the content of the "file_managed" table. Pls let me know if there more I can do to help you out.

--
Steinmb