special-members doesn't work

Describe the bug

I have a class histogram with a method __eq__, which I'd like to document.

When I write

.. autoclass:: histogram
    :members:
    :special-members: __eq__

it doesn't work (no such method appears in the documentation). I tried to add __eq__ to the list of :members: as suggested here, but it didn't work.

However, when I use a directive .. automethod::, it works, which looks like a bug. This works:

.. autoclass:: histogram
    :members:

    .. automethod:: __eq__

How to Reproduce

$ git clone https://github.com/ynikitenko/lena
$ cd lena
$ pip install -r requirements.txt
$ cd docs
$ # change the file 
$ vi sources/structures.py +55
$ make html
$ # open _build/html/index and see that it works / doesn't work

Expected behavior

special-members should work.

Your project

https://github.com/ynikitenko/lena

Screenshots

No response

OS

Arch Linux, 5.10.75-1-lts

Python version

3.9.7

Sphinx version

3.4.0

Sphinx extensions

'sphinx.ext.autodoc', 'sphinx.ext.autosummary', 'sphinx.ext.coverage', 'sphinx.ext.graphviz', 'sphinx.ext.mathjax', 'sphinx.ext.todo', 'sphinx.ext.viewcode', 'sphinxcontrib.napoleon',

Extra tools

No response

Additional context

Currently my readthedocs pages don't work because of another bug.

Reproduce the issue in the lena documentation using sources/structures.py, the autoclass directive, and :special-members: eq, then compare it with the working nested automethod example. Run make html and inspect the generated documentation; done means eq appears when requested through special-members.