Error creating correct drush site aliases for multi app projects

[acha5066]

We started our platform.sh project with just one app called drupal. We are running multisite and generating drush aliases worked fine. Eventually, we re-architected it to be a multi app project, with one app called drupal and the other called opensearch_proxy.

.platform/applications.yaml

drupal:
    // drupal config

opensearch_proxy:
   // opensearch_proxy config

Now when I tried to regenerate the aliases after creating a new environment it is not adding the correct --drupal suffix to the drush site alias.

Resulting alias:

environment-name:
  options:
    platformsh-cli-auto-remove: true
  root: /app/docroot
  user: project-id-environment-name-environment-id
  host: ssh.au.platform.sh
  uri: sitename

This doesn't work because it is missing the --drupal suffix. I get a

  Error Output:                                                                                                                                                                                           
  ================                                                                                                                                                                                        
  project-id-environment-name-environment-id@ssh.au.platform.sh: Permission denied (publickey).

If I manually edit the drush alias file to add --drupal suffix to user everything works. I checked the legacy-cli DrushAlias.php and it seems like it should account for multiple apps but it's not working.