Okay, I think I've figured out the Mac OS X issues. At least, I've corrected the one I've been able to duplicate. The way I implemented progress bar dialogs was causing intermittent problems and whole-program calibre crashes, but only on OS X.
I'm especially interested in hearing if anyone still gets the issue where the plugin stops while but doesn't crash.
New test version posted (direct link)
2016-04-24
- Fix for Mac OS X crashes - changes to progress bar dialogs implementation.
- Update translations.