When GitLab repositories are in subgroups[1], the matching GitLab references will not be displayed in the cross-reference field of the artifact.
From a technical point of view, we have to rework how references will be split and found from the cross-reference keyword and value. This will work well for references automatically stored by the GitLab integration (the one stored by the GitLab webhook parsing). The split of manually added GitLab cross-references will not benefit of this work. The current restrictions still apply on these.
[1] https://docs.gitlab.com/ee/user/group/subgroups/