Hello,
Like most people I have Javascript and cookies blocked by default for all sites except for a select few that I use regularly. Although *.youtube.com is in my allowed category, the comments section recently has failed to load.
The reason for this is the “Before you continue to YouTube” consent page has not appeared and therefore not been agreed/customized. In order to get the consent page to load you need to visit https://consent.youtube.com/ and enable Javascript and cookies for it. The page will likely throw up an Error 404 which is irrelevant, the main purpose is to enable Javascript and cookies for *consent.youtube.* for when Youtube presents a consent page specific to you/your region. Like pictured below…
Once done, opening up Youtube will present a consent page first and then the Youtube homepage with the comments loading again.
Enjoy.