Sign into Office portal with your admin work/school account.
Click the Admin tile>Users>Active users.
Check if that user account is in the list.
In the Office 365 admin center click Admin (Admin centers)>SharePoint.
Click user profiles>Manage user profiles>enter the problematic user account>Find.
Check if its user profile can be found.
Access http://YourSharePointSite/_layouts/15/people.aspx?MembershipGroupId=0, and check whether username of the problematic accounts are listed there. if not please add the user and try again .
One more possible reason may be that the user is logged in with an account that doesnt have permission, even if the error shows his work email.
If all above still failed , you may using correlation ID and contact Microsoft support .