Next.js doesn't hot reload

[alvinvoo]

Describe the bug
Next.js' HMR seems to have stopped working after I've included next.config.js.

To Reproduce

1. Do some changes in pages/
2. HMR doesn't reload

Expected behavior
HMR to reload everytime I change something.

Desktop (please complete the following information):

• OS: xbuntu 18.04
• Browser chromium 68.0.3440.106 (Official Build)

Additional context
I suspect it has something to do with below settings
HotModuleReplacementPlugin {
options: {},
multiStep: undefined,
fullBuildTimeout: 200,
requestTimeout: 10000 },
Is it because HMR has timeout while trying to reload? Because build takes too long due to inclusion of css loader? Probably can do some experiments.