sharepoint online – Check the User permission on a list item which has unique permission will show None if the user is added through office 365 group

I have a list item which has unique permission >> and we have created a new Office 365 group and add 6 members inside it >> then i assigned the Office 365 group to the list item with contribute permission >> but when i check one of the group members permissions on the list item, it gave me None.. although the user should have contribute on the list item through the Office 365 group.. is this a time issue since we created the group 15 minutes ago? or this is by design ?

enter image description here