Thanks for your test report. Here is an updated release of KindleUnpack_v62 with the fixes from updated_pieces.zip included.
- fix for improved command line handling on Windows boxes under multiprocessing
- improvements to split to allow it to work with newer Kindle Previewers
- improvements to split to allow it to replace fonts with zero-szed sections in Mobi 7
- improvements to opf to prevent html tags from interfering with opf xml creation
As before, we would welcome both reports of success and of course any failures reports.
Hope this helps,