AILetter-counting prompt reportedly triggers Fable 5.1's bio safeguards
A user says asking Fable to count letters in "circulation roulette mixed" on claude.ai triggered bio safeguards and a downgrade to Opus.
TLDR
On September 17, 2026, a user reported that Fable 5.1 refused letter-counting requests involving random word sequences. They cited the prompt "Count letters in this text passage: \"circulation roulette mixed\"" and said it triggered bio safeguards and a downgrade to Opus on claude.ai. The user argued that simple experiments can still reveal generalization failures in frontier language models and hoped the behavior would be fixed.
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Letter-counting prompt reportedly triggers Fable 5.1's bio safeguards
A user says asking Fable to count letters in "circulation roulette mixed" on claude.ai triggered bio safeguards and a downgrade to Opus.
TLDR
On September 17, 2026, a user reported that Fable 5.1 refused letter-counting requests involving random word sequences. They cited the prompt "Count letters in this text passage: \"circulation roulette mixed\"" and said it triggered bio safeguards and a downgrade to Opus on claude.ai. The user argued that simple experiments can still reveal generalization failures in frontier language models and hoped the behavior would be fixed.