GitLab lead_time_for_changes指标返回null问题求助

各位好，我最近在尝试查询GitLab项目的DORA指标，专门针对lead_time_for_changes这个指标，但遇到了棘手的问题。

我使用的curl查询命令如下：

curl --header "PRIVATE-TOKEN: glpat-xxx-xxx-1VGj" "https://gitlab.com/api/v4/projects/xxxx/dora/metrics?metric=lead_time_for_changes"

返回的结果里所有日期对应的value全是null：

[{"date":"2023-02-28","value":null},{"date":"2023-03-01","value":null},{"date":"2023-03-02","value":null},{"date":"2023-03-06","value":null},{"date":"2023-03-08","value":null},{"date":"2023-03-10","value":null},{"date":"2023-03-13","value":null},{"date":"2023-03-14","value":null},{"date":"2023-03-15","value":null},{"date":"2023-03-20","value":null},{"date":"2023-03-23","value":null},{"date":"2023-03-24","value":null},{"date":"2023-03-27","value":null},{"date":"2023-03-28","value":null},{"date":"2023-03-30","value":null},{"date":"2023-03-31","value":null},{"date":"2023-04-04","value":null},{"date":"2023-04-05","value":null},{"date":"2023-04-12","value":null},{"date":"2023-04-13","value":null},{"date":"2023-04-17","value":null},{"date":"2023-04-20","value":null},{"date":"2023-04-21","value":null},{"date":"2023-04-24","value":null},{"date":"2023-04-25","value":null},{"date":"2023-04-26","value":null},{"date":"2023-04-27","value":null},{"date":"2023-04-28","value":null},{"date":"2023-05-02","value":null},{"date":"2023-05-05","value":null},{"date":"2023-05-16","value":null},{"date":"2023-05-23","value":null}]

奇怪的是，其他DORA指标的查询都很正常，能返回有效的数据。而且不仅API调用没结果，连GitLab UI里的CICD分析页面，Lead Time for Changes这一项也完全没有数据显示。

有没有朋友之前遇到过类似的问题呀？麻烦给点思路或者解决方案，谢谢啦~

备注：内容来源于stack exchange，提问作者gitlab-question