After spending a lot of time debugging this, I discovered a very frustrating and reproducible bug:
When a single file contains many lines of code (around 1000+ lines), and you ask ChatGPT to make a modification that’s even slightly complex (not a refactor, just moderate consistency changes), it almost always returns:
“Unable to generate edits”
No matter how many times you retry, it fails — and ChatGPT just continues as if nothing happened, leaving you stuck.