Trouble logging in / creating account

We have a class attempting to login to MakeCode Arcade to save work, and some students are getting an error when trying to login; they are not presented a field to enter a username and password, just this error (see screenshot):

“Sign in failed. Something went wrong.”

Some students are able to get the sign in window, which makes this difficult to troubleshoot. All of the machines are iMacs running Big Sur, browsers are either Safari or Chrome (latest). I have also tested this on my 2020 MacBook Air running 12.1 in Safari and Firefox.

The URLs on the recommended allow list have also been created as allowed sites on our firewall.