This issue was found when debugging https://issues.redhat.com/browse/OCPBUGS-56596. When the cluster is registered with assisted-service in the agent-register-cluster.service, the first thing it does is register the cluster https://github.com/openshift/assisted-service/blob/master/cmd/agentbasedinstaller/register.go#L111 and then it sets any installConfig Overrides here https://github.com/openshift/assisted-service/blob/master/cmd/agentbasedinstaller/register.go#L123-L147.

If there is a failure in setting the installConfig overrides the service will terminate with a failure and then be restarted. The problem is, since the cluster HAS been registered, when it restarts it checks for the cluster, finds it, and skips the registration here
https://github.com/openshift/assisted-service/blob/master/cmd/agentbasedinstaller/client/main.go#L160-L164

the service then terminates successfully and the fact that a failure occurred when overriding the installConfig is lost.