A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.
Dear UserC55
Good day!
Thank you very much for the screenshot.
I understand your feelings very much. According to the screenshot and description you provided, you mentioned that the document library you created before had worked, so it is very likely that there is a problem on the server side leading to no work. I'm afraid this issue is related to the backend where it needs to further check by the related development team by collecting activity log for SharePoint document library. In this situation, I am sorry and recommend you to connect with the related development team where they can check the internal sources and investigate the issue further.
So, I request you to connect with your IT admin of your organization (How do I find my Microsoft 365 admin? - Microsoft Support) and ask them to raise a new service request from the Microsoft 365 admin center so that the related development team will connect with you and investigate the issue further.
Reference: Get support - Microsoft 365 admin | Microsoft Learn
Apologies for redirecting you to the related development team support as the moderators in this community have limited resources to check the backend information, and to get the fast and better assistance we requested for it.
Thanks for your cooperation.
Sincerely,
Tin | Microsoft Community Moderator