I'm trying the Azure Security Center integration with AWS, which was in public preview at Ignite2020 by following these steps:
https://docs.microsoft.com/en-us/azure/security-center/quickstart-onboard-aws
I'm having a problem with the "Connect AWS account" screen.

No choices appear in Subscription.
In addition, nothing is displayed in the External ID.
I have an Azure subscription for a free period and am an account owner.
Azure Security Center Deffender is enabled.
Does anyone know the cause?