I created a group "mygroup" Created a repository "myrepository"
Add patch .gitlab-ci.yml@mygroup/myrepository as documented - https://docs.gitlab.com/ee/ci/pipelines/settings.html#custom-ci-configuration-path but gitlab ci does not see this file from another repository.
Maybe we should do something else?
I worked with the same problem.
You should change
mygroupandmyrepositoryvisibility tointernalorpublic.change group visibility
change repository visibility