CI has no access to project's container-registry?

In a Gitlab project, say cogumbreiro/c-to-json, I have a container called registry.gitlab.com/cogumbreiro/c-to-json/clang9in the project’s registry and I would like to use that container in my .gitlab-ci.yml script (of the same project).

I have tried using the full name of the registry,

---
image: registry.gitlab.com/cogumbreiro/c-to-json/clang9:4066978

and got the following error:

ERROR: Preparation failed: Error: No such image: registry.gitlab.com/cogumbreiro/c-to-json/clang9:4066978 (executor_docker.go:199:0s)

I have also tried removing registry.gitlab.com from the container name:

---
image: cogumbreiro/c-to-json/clang9:4066978

but got the same error.

My questions are:

  1. Am I doing something wrong, or is this workflow unsupported?
  2. Does this mean that Gitlab.com’s CI only supports Docker-hub.com’s registry?

Thanks!