Stylelint seems to not respect `.stylelintignore` at project root

When running the linterbot with stylelint enabled, any paths ignored by a `.stylelintignore` at the project root are not properly ignored by the linter. That is, running `npx stylelint content/**/*.scss` returns no errors, but HM Linter is returning errors in files while should be excluded by the `.stylelintignore`.

I don't initially see what the error is. What is the first step I should take in troubleshooting this issue?