Hi Abrar Hussain2,
Thank you for reaching out to the Microsoft Support Community.
I'm here to help with your problem.
Ensure that the Organizational Units (OUs) where the groups and users are located are not blocked from inheriting group policies.
And, do you have any event logs or hard copies? We would like to investigate your problems in more detail.
Here are some references about GPO.
Applying GPO to Security Group not taking effect - Microsoft Q&A
Best regards,
Yu