Specific AD group does not get permission in Sharepoint Online

Question

I want to restrict access to a site in Sharepoint Online.

I have disabled inheritance and created a new Contributor Sharepoint group, called [Site] Members.

When I add Active Directory (AD) group A to this Sharepoint group, and use "Check permissions" it shows the expected result. But when I add AD group B, "Check permissions" shows that its members don't have access.

Both AD groups A and B are non-nested, meaning they only contain users, not other AD groups. They are also both Security groups and similar in every way.

If I add users from group B to the Sharepoint group directly, then "Check permissions" reports that they have access.

Why doesn't group B work?

Answer 1

Apparently, the users in Group B had both normal and Administrator user account types, and group B only contained the latter.

Answer 2

Please have a check on user information list. If group B is listed there, please remove it and re-grant access to Group B.

If Group B is not in that list, try to add Group B with powershell Add-SPOUser and see if the issue remains.

You can submit a service request for further help from MS support team.

Update: Information about User information list.

If nothing helps, you can simply ask for a service request and the MS support team will provide further help.