Hi Kevin,
Thank you for posting your issue here.
Firstly, I’d like to convey this feature is a new feature to the Quick Edit function in SharePoint/Microsoft List.
Although the feature status in Microsoft 365 Roadmap is marked as launched, actually it might take some time until all the users have access to this function.
If the user is not enabled the target release for select users on the tenant level, he/she may not receive the feature for now. And a Global admin can check the release preference settings in the admin center.
If your issue persists, to narrow down your issue, we need to confirm the following information with you.
To narrow down your issue, we need to confirm the following information with you.
1. May I know is the SharePoint site pages that you granted edit permission is in the classic experience? If the sites are in classic experience, he may not see “Edit in grid view”.
2. May I know if the user has permission to edit a SharePoint list? To check this, on the list page and then click the gear> list settings> Permissions for the list to see whether the user is in the permission list and members group or not.
3. May I know could the user see “Edit in grid view” from other sites?
4. May I know could the other users with the same permission see the function on the same site page?
5. What is the new user’s SharePoint sites Page look like? Would you mind providing a screenshot of the site?
Best Regards,
May