Since your domain status is ‘FAILED_NOT_VISIBLE’, I would recommend you to see the Google-managed SSL certificate domain status section [1] on the troubleshooting SSL certificates page.
It is worth mentioning that Google Groups is a place for non-technical how-to questions (where you're likely to find information like service status updates and release notes, and ranging from book recommendations to creative shortcuts) [2].
Therefore, If the issue still persists after following the recommendation, I would recommend you to consider reaching out to Stack Exchange sites [3] (e.g. Server Fault [4] or Stack Overflow [5]) where Google also participates that can help you find answers and troubleshoot problems.
If you find any indication of a GCP issue, you may also report [6] the issue with Issue Tracker with all the details [7] (omitting PII/sensitive information).