I’m trying to integrate our build to slack and set SLACK_WEBHOOK in project Environment Variables, but seems the circleci job is unable to get the variable and report: NO SLACK WEBHOOK SET, here is the failed build and setting:
Apologies! I missed the build link you initially posted.
The Slack integration appears to be properly configured indeed.
However, I see that build was triggered by a forked pull-request. I suspect the issue stems from the fact that the project is not configured to pass secrets to builds from forked pull requests.
That said, I strongly advise reading about that feature before deciding to enable it.