My SSL certificate had been issued on AWS Certificate List but my website still haven’t secured with the https hyper link nor having the lock icon. Am I missing something?

Is the ACM certificate set up in ALB or CloudFront?
Try clearing your browser cache to be sure.

I am going to assume your wordpress is behind a ALB and you have port 80 and 443 as listeners on the ALB.

I will also assume you have not configured port 80 to redirect to 443 on the load balancer