WARNING: Unknown type: placeholder

Hi all, I have a Python project that uses sphinx and today I got this warning, which I am treating as error on my CI, about an unknown type.
I can't find information anywhere about which file this is coming from, which line, which class or whatever. This is kind of a message in the middle of the build that I can't seem to root cause to fix it.

I am deleting huge amounts of docstrings to see if I can isolate the problem, but without knowing where it comes from, it is just impossible to get it fixed.

This is the piece of log

[AutoAPI] Ignoring directory: /scratch/tfernand/dev/ge/quark/quark/contrib/dummy/
[AutoAPI] Ignoring directory: /scratch/tfernand/dev/ge/quark/quark/contrib/onnx_utils/
[AutoAPI] Ignoring file: /scratch/tfernand/dev/ge/quark/quark/contrib/__init__.py
[AutoAPI] Reading files... [100%] /scratch/tfernand/dev/ge/quark/quark/torch/algorithm/awq/modules/act.py
WARNING: Unknown type: placeholderscratch/tfernand/dev/ge/quark/quark/torch/kernel/hw_emulation/hw_emulation_interface.py
WARNING: Unknown type: placeholderscratch/tfernand/dev/ge/quark/quark/torch/quantization/tensor_quantize.py
[AutoAPI] Mapping Data... [100%] /scratch/tfernand/dev/ge/quark/quark/torch/algorithm/awq/modules/act.py
[AutoAPI] Rendering Data... [100%] quark

At first I though this was coming from hw_emulation_interface.py or tensor_quantize.py, but these files now dont have any docstring, so it can't be it. Also act.py already didn't have docstrings.

Any ideas?

just realized this is being discussed as https://github.com/readthedocs/sphinx-autoapi/issues/180, it was closed but without any conclusion

Start by reproducing the warning during the AutoAPI build and inspect the reported paths, including quark/torch/algorithm/awq/modules/act.py, hw_emulation_interface.py, and tensor_quantize.py. Compare the warning behavior with the discussion in issue #180; done means identifying the source location or correcting the warning so CI can diagnose it.