EKS cluster not accessible from an EC2 instance in different account

Question

I've created an EKS cluster with an IAM role and I'm trying to access the cluster from my CI build agent which is present in a different account. My CI build ec2 instance is not being to able identify the EKS cluster when I attach an Instance profile and a trust relationship with the role used to create the EKS cluster. But when I go with User authentication, I'm getting the expected output. I want it to be accessible with the IAM role instead of the IAM User. Any thoughts or help would be appreciated. Note: The EKS cluster is created using Terraform with an Assume role authentication.