GitLab page is not served from group (while it is succesfull from user namespace)!

I try to build a page for a project within a group however although the whole build process (and the pages job) succeeds the page is not deployed. I tried the same page source + (with some minor modifications at script) in a private repository in my user account’s namespace and it worked! The pipline here reports two jobs having completed successfully: pages and pages:deploy. When I run a pipeline with similar settings for the group project then only the pages job is reported and the pages:deploy job is missing completely (also CI settings are similar!).
Note that I once had a page for the group itself which I removed ~15min. prior to the pipeline. When I checked the group URI it reported 404 so I supposed that the domain has been freed. However it’s not deploying the page.