I get no diagnostic information from ruff

[Onturenio]

Hi, I'm using coc-pylsp with the third-party python-lsp-ruff. This setup has worked fine for some time. Now, I just realised I'm getting no linting whatsoever. I'm not sure why this is happening now, when it started, or how to debug the situation.

My coc-settings.json is:

{
"pylsp.enable": true,
"pylsp.plugins.pycodestyle.enabled": false,
"pylsp.plugins.pyls_isort.enabled": false,
"pylsp.plugins.flake8.enabled": false,
"pylsp.plugins.pydocstyle.enabled": false,
"pylsp.plugins.pyflakes.enabled": false,
"pylsp.plugins.mccabe.enabled": false,
"pylsp.plugins.yapf.enabled": false,
"pylsp.plugins.ruff.enabled": true,
"pylsp.plugins.ruff.formatEnabled": true,
"pylsp.plugins.ruff.extendSelect": ["E", "D", "C90", "I"],
"pylsp.plugins.ruff.ignore": ["E265", "E266"],
"pylsp.plugins.ruff.format": ["D", "C90", "I"],
"pylsp.plugins.ruff.preview": true,
"pylsp.plugins.ruff.lineLength": 79,
"pylsp.builtin.installExtrasArgs": [
"flake8",
"yapf",
"mccabe",
"pycodestyle",
"pydocstyle",
"pyflakes",
"pylint",
"rope"
],
"pylsp.builtin.enableInstallPythonLspRuff": true,
"pylsp.builtin.enableInstallPylsIsort": false,
"diagnostic.messageTarget": "float",
"diagnostic.checkCurrentLine": true,
"suggest.enablePreselect": false,
"suggest.noselect": true
}

I have run :CocCommand pylsp.builtin.install to make sure everything is fresh installed, and indeed the directory has the right binaries:

> ls ~/.config/coc/extensions/@yaegassy/coc-pylsp-data/pylsp/venv/bin/
activate       Activate.ps1  get_objgraph            pip      pycodestyle  pylint         pyreverse  python3.11  undill
activate.csh   flake8        isort                   pip3     pydocstyle   pylint-config  python     ruff        yapf
activate.fish  get_gprof     isort-identify-imports  pip3.11  pyflakes     pylsp          python3    symilar     yapf-diff

Still, when I run :CocDiagnostics I get an empty window.

The output from :CocInfo is

2024-09-18T10:09:44.761 INFO (pid:1605552) [attach] - Request action: fillDiagnostics [ 3 ]
2024-09-18T10:09:51.370 INFO (pid:1605552) [attach] - receive notification: highlight []
2024-09-18T10:09:52.490 INFO (pid:1605552) [attach] - receive notification: highlight [] 
2024-09-18T10:09:54.606 INFO (pid:1605552) [attach] - receive notification: showInfo []

Which I'm not sure how to interpret, but that [ 3 ] seems suspicious.

Any idea on what's happening or how to debug this?

PS: I'm aware this rather a question, not an issue. If you think this is not a proper place to pose this question, let me know and I'll be happy to pose it somewhere else.