As seen on T293741 (and permissions issues on T296381 may be related), users who are:
- at the owner level in a group
- and that group is invited to another group at owner level
...don't seem to be able to fork or transfer a project to that group.
As a learning experiment I wanted to transfer this repo to https://gitlab.wikimedia.org/repos/generated-data-platform.
I tried following the doc at https://gitlab.wikimedia.org/help/user/project/settings/index#transferring-an-existing-project-into-another-namespace.
However, in the settings panel I'm only given the option to transfer to https://gitlab.wikimedia.org/people/wmf-team-platform-engineering (instead of my desired target).
I checked and this also doesn't allow forking to that namespace for @gmodena's user, although it was available to me as an admin.
This likely isn't a large problem for creating brand new repositories, but it's a hassle for people moving a project from a personal namespace to something more official, and probably also for various maintenance tasks.