tensorflow_script_mode_horovod - CloudFormation template is not working

Hello.
The last part of this notebook (Setup VPC infrastructure) does not work for me. The stack fails to create. Here is the full error:
```
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
in ()
42
43
---> 44 subnets, security_groups = create_vpn_infra()
45 print("Subnets: {}".format(subnets))
46 print("Security Groups: {}".format(security_groups))

in create_vpn_infra(stack_name)
25
26 if describe_stack["StackStatus"] != "CREATE_COMPLETE":
---> 27 raise ValueError("Stack creation failed in state: {}".format(describe_stack["StackStatus"]))
28
29 print("Stack: {} created successfully with status: {}".format(stack_name, describe_stack["StackStatus"]))

ValueError: Stack creation failed in state: ROLLBACK_IN_PROGRESS

Here is my CloudFormation IAM policy attached to the role:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"cloudformation:*"
],
"Resource": "*"
}
]
}
```
I can't see any debug/log information in AWS console's view of CloudFormation stack.
How do I debug? Can you provide an example of IAM CloudFormation policy that you have under which this deployment succeeded?