I just tried it out, and it's working.
The server that grants authorization isn't robust, likely, so it it gets something that's not formatted correctly, it'll just throw a 500 likely.
I'd guess probably extensions or browser settings, more likely extensions than 3rd-party cookies. Note I had uBlock Origin enabled, and it worked, but I do find uBlock Origin plays nicer with sites compared to other similar extensions.
A firewall, for example common in workplaces or if you're using a firewall, would likely interfere too.
Check into those and I hope that helps!