Azure subscriptions that have been created specifically to house secure data (PHI, HIPAA data, etc.) have a policy applied that blocks the creation of new, as well as the assignment of existing Public IPs to resources.
When you attempt to create or assign a public IP to a resource, you should see an error that is similar to the following:
Failed to save network interface Failed to save IP address changes for network interface '<network interface name>'. Error: Resource '<resource name>' was disallowed by policy.
Exemptions for this policy can be granted on a resource-by-resource basis by filling out this form.
NOTE: You will need to create your resource prior to filling out the form, so that it may be marked as "exempt."