I think this issue has to do something with Europe, today i fixed this issue on my device.
Steps to fix:
1. Change Region Settings to Singapore (Settings App -> Additional Settings -> Region -> Singapore)
2. Use a Singapore VPN (Don't disconnect the VPN till the end.)
3. Log out from your Mi Account
4. Click on create an account, make sure your VPN is still connected and choose Country/Region to Singapore and create a new mi account
5. Go to Mi Unlock Status and it should work now
These are the steps which I followed to get this issue fixed. Tell me if it works for you.