There seems to be an issue with the Media Converter 6.5 and V4 BB...
Do you have Artlantis Media Converter 6.0 ?
As a work around, If you have it try to convert the V4 BB with version 6.0, I have tested it and it works the BB are not cut in half...
If not I can send it to you, on which platform are you working ? Mac or Windows ?