Are the hands that aren't importing properly being imported in Build 3 or Beta 19? You can purge selected sessions in Beta 19 by clicking Database --> Database Management, clicking on your database and clicking "Purge". This will let you select and remove certain sessions.
If these hands were imported in Build 3, please try purging and reimporting in Beta 19. If they were imported in Beta 19, please create a
support ticket and attach the hands in question so that we can look into this issue and get it resolved asap.