I’ve also had it refuse to OCR public-domain books that included content that it didn’t like, such as references to prostitution in 19th-century books about Japan.
I had one session where Claude refused to continue after it hit some kind of guiderail restriction. I couldn’t see what the trigger was, so I started a new session, gave Claude the link to the previous session, and asked it to diagnose the problem. This new Claude said it couldn’t view the exact guardrail issue, but it did suggest a workaround that turned out to be effective.