Private messages doesn't grouped + all inbox messages marked as «new»

All the messages from dialogs, even with the same threads imports separately. I've got all the messages, inbox and sent mixed together in one column (may be, this is the way they should, but it seems, that in 6.x releases everything was ok.)

The most terrible thing, that all users messages (even that was read in phpbb) are marked as new after import. So user get message «You have 152 new private messages»

Tested with the latest releases of phpbb2drupal and privatemsg and in the dev versiouns of both ones. (and phpBB 3.0.x)