Scheduled articles are not published when publishing the corresponding issue

Describe the issue or problem
Not all articles assigned to a certain issue are published when the issue is published. Some articles remain as “scheduled” in the Submission / Archives tab. To get them published, they need to be unscheduled and each one needs to be published manually.

Steps I took leading up to the issue
During issue preparation, I assigned articles to a future issue (Publication → Issue → Asssign to issue). → a) articles are shown in the preview of the respective issue and can be ordered b) in the submission overview, articles are moved from “All Active” in “Archives”. There they are labeled as “Scheduled”. After publishing the issue (Issues → Future issues – Publish Issue), some of the assigned articles are in “Archives” with the status “Published” while others remain “Scheduled”.

What application are you using?
OJS, but I had the same problem in OJS 3.2

Additional information
I do not have screenshots.