Hello @ddollar,
With the latest rack version, setting EncryptEbs=Yes leads to EC2 instances not being able to start due to the following error message from the ASG logs:
Launching a new EC2 instance. Status Reason: the encrypted flag cannot be specified since device /dev/xvda has a snapshot specified. Launching EC2 instance failed.
This issue is present since at least version 20190308201344.