Root cause: net_generator/feature_utils/mel_converter parameters were loaded
in ComfyUI's inference_mode; operations on inference tensors propagate the flag,
so conditions computed from tainted weights were also tainted. checkpoint()
with use_reentrant=False then failed trying to save inference tensors during
the backward recompute pass.
Fix: _strip_inference() clones all params/buffers of all three models before
any forward pass, and _clone_nested() cleans any residual inference flags in
the conditions/empty_conditions output tensors.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Ethanfel
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