Issue with Associating EFF Attribute Group at Parent Item Class level

Summary:

My Item Class structure looks like as below:
Root Item Class
……………….|-Class A
……………….…….|- Class P
……………….…….|- Class Q
……………….…….|- Class R
I have an EFF Attribute Group with one required attribute associated at Class A under "Pages and Attribute Groups" → "Attribute Groups".
Added Attribute Group to Pages tab of Class P and Class R only.
While creating Item for Class Q, getting error to fill-in required attribute.

Content (please ensure you mask any confidential information):

Expected Result: I should not be prompted to create required attribute as that Attribute Group is not associated to Item Class "Class Q".