A handful of books "just won't align" — how do I actually narrow down why?

I have a few books in my library that never align properly no matter how many times I retry. Everything else works. Is there an alternative alignment method, or some way to figure out what's different about these books?

Resolution: There is no alternative alignment engine to switch to; "won't align" covers several distinct failure modes and you have to identify which one a given book hits. Work through it in order: read the server logs to find which phase fails — "transcode audio", "transcribe audio" or "alignment" — since a failure in transcription needs a completely different fix from a failure in alignment. Then inspect the transcription output for that book and check it actually matches the narration; garbage or repeated hallucinated text is a common cause, and re-transcribing with a different or larger model often fixes it. If the book is a translated work, verify the audiobook and the ebook are the *same translation* — mismatched translations will never align and this is easy to miss. Expect imperfection even on good books: most chapters miss a sentence or two, usually at the start or end of a chapter. Some users on macOS or Apple silicon also try storyalign as a second opinion on a specific problem book.