Could you install this new version of the plugin (attached to this post) and try to convert a book that failed? I'd prefer if you try Im grünen Tann by Arthur Achleitner since that's the one you sent me, it's easiest for me to refer to that book.
I don't expect this to fix the problem, but it should give me more information I can use. Try both on the computer where it's failing and one where it was working. If the computer where conversion fails is 32-bit, try to also use a 32-bit computer where conversion has been working, just to minimize differences when I compare the log files. Upload the log files from both computers to
https://www.dropbox.com/request/g0Q3WAW4jIcCYgkTFBt2
To install a new plugin from a file:
- Open calibre's preferences
- Under "Advanced", choose "Plugins"
- Click "Load plugin from file" and find the plugin ZIP file you downloaded