The Azure Subscription list used to assign Subscriptions to FlexOrgs is stuck in a loading state, but Azure Subscriptions are visible in the asset report.
This can be caused by an Azure Subscription missing a value for the Subscription Name. Check the assets report for any Subscriptions with no name and update the Subscription in the Azure Console. If the Subscription is no longer available in the Azure Console, contact support to have the name updated in CloudHealth.