The response / conversation gets blocked by the guardrails with "API Error: 400 Output blocked by content filtering policy"

At first I thought it was something in the scanned content that was being flagged, but it was the attempt to transcribe that was itself being flagged. Anthropic mention it on their pages:

"Anthropic takes these steps because Claude’s purpose is to generate new content and ideas, not to reproduce content that already exists."

https://privacy.claude.com/en/articles/10023638-why-am-i-rec...

Side note - Claude itself is not aware of this policy, and is unable to see the API responses - the turn just ends. Which turned into a really bizarre failure state where Claude thought I was gaslighting it and kept insisting it could do the work and even had the entire text in memory. Every time it would go to show me and prove it, it would hit API Error 400. I was only able to convince Claude by showing screenshots of my Claude Code screen output so it could see that I was seeing API errors. I've never seen Claude get into that angry & snarky state before, and I hope it doesn't happen again.