List items: Enable edit, disable create item

To the best of my knowledge, there is no limit in SharePoint Online that prevents a permission level from working simply because it’s assigned to a group with many users. A group with 75 users is completely normal and far below any threshold that would cause permission failures.

I also tried to reproduce the issue, but unfortunately I only have 5 to 10 users in my tenant. In my environment, everything works correctly. Users can edit items without having the option to add new ones.

Here is how I created the permission level: I copied the existing Contribute permission level and created a new one called Contribute – No Add. The only change I made was unchecking Add Items; I did not modify any other settings in that permission level.

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