Blocking mode: nightmare mode - uBlockOrigin/uBlock-issues GitHub Wiki
Nightmare mode is when you block everything, except the main document. All secondary resources are blocked. As a result, most sites are broken. I personally advise against using this mode, since there is no real advantages from the hard mode. If you want to use uBlock Origin (uBO) in this mode, you are probably better off using uMatrix or Policeman, which will give you a higher granular control over network requests than what uBO allows you.