verified this bug on v3.11.50
# oc idle test-service
The service "z1/test-service" has been marked as idled
The service will unidle ReplicationController "z1/test-rc" to 2 replicas once it receives traffic
ReplicationController "z1/test-rc" has been idled
# curl 172.30.201.18:27017
Hello OpenShift!
# oc get ep
NAME ENDPOINTS AGE
test-service 10.129.0.12:8080,10.130.0.10:8080 1m
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHBA-2018:3743