I was able to resolve the issue. Apparently, one of my servers was on an older build that was not reading the replication features from the license file. After updating the issue is resolved.

I am experiencing the same issue. I am using the free 2-node license for Hyper-V. I have checked and both nodes list the license type as Enterprise HA unlimited and 2 servers per license. I just rebooted each node and Add Replica is still greyed out.