CI bot comment does not contain preview link

🐛 bug report

Preflight Checklist

• I have read the Contributing Guidelines for this project.
• I agree to follow the Code of Conduct that this project
  adheres to.
• I have searched the issue tracker for an issue that matches the one I want
  to file, without success.

Description of the problem

When opening a new PR with codesandbox CI, the bot comment doesn't contain the preview link. Not sure if I'm missing a config, the sandbox builds properly and the comment only links to the build log. Is there another way to find the generated sandbox?

How has this issue affected you? What are you trying to accomplish?

The codesandbox CI app is installed on my repo, a new sandbox should be generated for each PR. I switched the template I was using to a different directory to build that one instead but I cannot find the new generated sandbox link.

To Reproduce

Here is the link to the PR with the missing sandbox preview link.

Link to sandbox: link (optional)

A sandbox link was not generated.

Your Environment

Start with the linked reproduction pull request and inspect how the CodeSandbox CI app is configured for its preview build and bot comment. Confirm whether the sandbox is generated successfully but its URL is omitted, then verify that a new pull request comment contains a usable preview link.