You are working as a solution architect for a customer in Frankfurt, which uses multiple compute instance VMs spread among three Availability Domains in the Oracle Cloud Infrastructure (OCI) eu-frankfurt-1 region. The compute instances do not have public IP addresses and are running in private subnets inside a Virtual Cloud Network (VCN). You have set up OCI Autoscaling feature for the compute instances, but find out that instances cannot be auto scaled. You have enabled monitoring on the instances.
What could be wrong in this situation?