Using Codex to Diagnose GRPO Training Collapse: Finds the Bug, Lacks the Fix

ivan_bezdomny · x · 2026-08-02

An AI researcher shared an experiment using Codex to troubleshoot a sudden collapse in a GRPO reinforcement learning run. According to the developer, Codex successfully analyzed the training logs to identify the timing and describe how the failure occurred.

However, its best suggested fix was simply to lower the learning rate. The researcher noted that while fine-tuning APIs are useful, understanding how models fail still requires deep foundational knowledge.

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