[int_19h]

It's because they are using a third-party (cookielaw.org) cookie to record the your choice. So if your browser is configured to not allow third-party cookies - e.g. Safari's "prevent third party tracking" and similar options in other browsers, or PiHole and AdGuard - this breaks them.

And yes, it's a known issue going back several years. The official response is "it affects less than 1% of our users, so fuck you".

[LegionMammal978]

How would they even be able to fix it, short of redirecting all their domains to stackexchange.com subdomains (and causing a colossal branding mess and making everyone mad)? Almost by definition, anything that would allow them to know you've accepted cookies on a different domain would be a form of tracking that all the anti-tracking stuff would clamp down on.

[int_19h]

The fix would be to use a per-domain cookie, and don't expire it in just a few days.

[kristianp]

Aren't 3rd party cookies blocked by default in Chrome? Obviously not.

[cedws]

Must be positioning themselves for a Microsoft acquisition!