Thank you for the tip, I managed to get my keys back with this "trick":
Here is what I did exactly:
- Log in with the account I want to use, try to go to https://account.microsoft.com/devices/recoverykey . Get the error message.
- Click my avatar on the top right, select "Sign in with different account", then click create new one and follow the instructions to create a new account.
- With the new account go to https://account.microsoft.com/devices/recoverykey again to see that there are no Bitlocker keys.
- Clicking the avatar again switch to the old account (if the other account doesn't show up, click Sign in with different account again and type in the email of the old account).
- After successfully switching back to the old account, my BitLocker recovery keys have shown up.
I have a personal account it might be different for enterprise users.
Hopefully it works for others, so they can get into their systems while MS is fixing this.