Codequality report is not visible in Pipeline Code Quality tab, or MR

In our company self-hosted Enterprise Gitlab instance, I have a custom tool that’s outputting a Code Quality report in the format described here, Code Quality | GitLab

The issue is that it keeps saying there are no issues, even though there are some in the MR report. I’ve followed all the required steps, but alas, nothing is happening, both in the MR widget and the Pipeline tab, where it’s supposed to be visible.

The job that generates the report uploads it as a codequality artifact, as described here, GitLab CI/CD artifacts reports types | GitLab

The job has run on the main branch, and also in the MR I’m testing with, and in both cases, the report has been generated and the job logs say that it’s been uploaded successfully as codequality report.

There is a difference in the number of issues between the main branch and the MR.

When I try to call the Gitlab Graphql API to see if there are any parsing errors or something, it just says that the codequality report is null. (using the query here, Code Quality | GitLab)

Could anyone help with this? Any ideas what else I could be missing? There are no errors visible anywhere, so I don’t think it’s a report schema issue, as I’ve followed it exactly.