Getting error loading postcss plugin when running hugo with --source

Seems like postcss is trying to load the plugins from the directory that i am running hugo, so i cannot run hugo from a different directory with the --source flag. Tried with version 0.75 and latest. Also I am using the docsy theme GitHub - google/docsy: A set of Hugo doc templates for launching open source content.

hugo -s site
Start building sites … 
hugo v0.87.0-B0C541E4+extended linux/amd64 BuildDate=2021-08-03T10:57:28Z VendorInfo=gohugoio
Error: Error building site: POSTCSS: failed to transform "scss/main.css" (text/css): Error: Loading PostCSS Plugin failed: Cannot find module 'autoprefixer'
Require stack:
- /root/.docs/noop.js

    at load (/root/.docs/site/node_modules/postcss-load-config/src/plugins.js:28:11)
    at /root/.docs/site/node_modules/postcss-load-config/src/plugins.js:53:16
    at (<anonymous>)
    at plugins (/root/.docs/site/node_modules/postcss-load-config/src/plugins.js:52:8)
    at processResult (/root/.docs/site/node_modules/postcss-load-config/src/index.js:37:14)
    at /root/.docs/site/node_modules/postcss-load-config/src/index.js:151:14
    at async Promise.all (index 0)

Yes, this is a known current limitation/bug. There is an open GitHub issue about this, which I’m not totally sure how to fix.

To cut a long story short, in your case you need to cd into the project folder and run hugo without the source flag.

It somehow works on my computer (mac), and just seeing the issue on a linux build container. But not sure why