Creating: Uhm, right I edited https://phabricator.wikimedia.org/transactions/editengine/projects.project/view/4/ to make that field visible on https://phabricator.wikimedia.org/project/edit/form/4/ (but not sure which URL you use).

Regarding editing: I have no idea how to reproduce; that field has been visible for me before when editing. Please provide more info.

Creation now shows, The editing form (#9) doesn't show it

Ah, thanks. I get https://phabricator.wikimedia.org/transactions/editengine/projects.project/view/6/ (I think... I click Manage > Edit Details and then Configure Form > Edit Form Configuration to find out that Form number as Forms are highly confusing to me.)
You seem to get https://phabricator.wikimedia.org/transactions/editengine/projects.project/view/9/ .

I do not know why and what's the exact difference between them. Maybe @mmodell has an idea?

Hi all! I'm getting the same issue. I'm not being able to set source repo for subproject Web2Cit-Core.

On the other hand, I was able to set the source repo for subproject Web2Cit-Server upon creation, but I'm not able to change that now (just an example, I don't need to change it).

Any news?

Form 6 is more restricted, it's for policy-admins not project-admins

I enabled the repository field on form 9.