Router traffic not distributing in advanced deployment strategies (A/B testing or Blue/Green deployment)

Issue

Even after allowing 100% of weight to the ab-example-a service, traffic is still going to the ab-example-b service.

~~~
$ oc edit route <route-name>

metadata:
  name: test-route
spec:
  host: ab-example.my-project.my-domain
  to:
    kind: Service
    name: ab-example-a
    weight: 100
  alternateBackends:
  - kind: Service
    name: ab-example-b
    weight: 0
~~~