Simply put;
SASS = styling works beautifully.
styled-components = styling broken on initial page load, but applies on HMR.
Install via npx create-nx-workspace@latest sass --preset=next
Selecting SASS for styling

(note: styled-components unavailable here)
Remove the scss default

Add another app, selecting styled-components

Serve and check the apps
| nx serve styled-components | nx serve sass |
| - | - |
|
|
|
@nrwl/angular : Not Found
@nrwl/cli : 8.7.0
@nrwl/cypress : 8.7.0
@nrwl/eslint-plugin-nx : 8.7.0
@nrwl/express : Not Found
@nrwl/jest : 8.7.0
@nrwl/linter : 8.7.0
@nrwl/nest : Not Found
@nrwl/next : 8.7.0
@nrwl/node : Not Found
@nrwl/react : 8.7.0
@nrwl/schematics : Not Found
@nrwl/tao : 8.7.0
@nrwl/web : 8.7.0
@nrwl/workspace : 8.7.0
typescript : 3.4.5
node: v12.12.0
npm: 6.11.3
3rd-party libraries: none
use case that failed: check above reproduction steps 鈽濓笍
repro: https://github.com/zynchro/nx-issue-repro-styled-components

I have the exact same problem. Styles from styled components are missing after initial load, but they are applied after HMR.
Same issue here
My issue was that server and client had a different classNames. I found a solution here:
https://github.com/zeit/next.js/issues/7423
It's possible if you override the document class and provide the babel plugins.
See example here: https://github.com/jaysoo/react-ssr-example/tree/master/apps/next-app
Going to close this issue since there is a solution, but we might look at enhancing the generated code when styled-components is chosen. Cheers!
Am I supposed to see styled-components as an option because I don't? In this case, is it okay to add ti manually myself? I'm new to nx, how is that going to affect working with the nx commands? 
Most helpful comment
It's possible if you override the document class and provide the babel plugins.
See example here: https://github.com/jaysoo/react-ssr-example/tree/master/apps/next-app
Going to close this issue since there is a solution, but we might look at enhancing the generated code when
styled-componentsis chosen. Cheers!