Customer created a custom ClusterRole to give to their pipeline admins. Their admins are able to deploy/manage the pipelines, but cannot see the metrics in the developer console -> pipelines -> metrics tab.

In testing to reproduce this, I noticed the same is true even for project admins. After running the below:

$ oc policy add-role-to-user admin user-ns-admin -n myproject

The user "user-ns-admin" can see the pipeline in the developer console, can start new runs, etc. But I CANNOT see the metrics in the metrics tab.

According to the documentation [1], the user should need "cluster administrator or a user with create and edit permissions" to manage pipelines in the Developer Console, so I think project admin counts as having create and edit permissions?
[1] https://docs.openshift.com/container-platform/4.9/cicd/pipelines/working-with-pipelines-using-the-developer-perspective.html

If this is expected behavior, what are the exact role requirements for viewing metrics? If this is expected behavior I can create a knowledgebase solution to reflect the requirements.

I can reproduce at-will, let me know if you need to take a look.