Regarding page naming, this is a known issue. I tested it in my environment and did not reproduce your situation. When the page is edited, you will be prompted to add a title when you click publish. So by default, the page without a title is accidentally closed. After you add a title to the page without a title, can the New function work properly? If the problem persists, you need to check the backend to see what went wrong. So we recommend you directly create a support ticket from Microsoft 365 Admin. The support team over there has the correct escalation channel, they can involve more resource and investigate the behavior from back end as fast as possible. They also can check the behavior on your end remotely. For reference: Get support - Microsoft 365 admin | Microsoft Docs
Good day!
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