This issue is resolved in VMware Aria Automation 8.12.2.
Note: This version will upgrade the "yaml" library to 2.2.1 and fix the calculation of indentation count from comment strings.
If you are unable to upgrade to 8.12.2 or higher, remove the comments from the beginning of the YAML.
Reference Jira Link: https://jira.eng.vmware.com/browse/VRAE-44041
This is a change to the template and can be made on demand with no known impact on the running system.