Hi, good day!
Since you're able to sign in to your Microsoft account, this may be a temporary issue with Microsoft's Recovery Key page. Other users have also reported similar behavior.
For now, I'd recommend trying again later. You can also try opening the Recovery Key page in an InPrivate or Incognito browser window, as some users have found that this works.
If the issue continues, please submit feedback through the Feedback Hub app or use Report a problem if you're on the website so Microsoft is notified. The more reports they receive, the more visibility the issue gets.