Maybe because the k8s ports of the service with microk8s are wrong: TCP and not UDP
When using the official jaeger operator https://www.jaegertracing.io/docs/1.14/operator/#installing-the-operator-on-kubernetes:
simplest-agent ClusterIP None <none> 5775/UDP,5778/TCP,6831/UDP,6832/UDP 13s
simplest-collector ClusterIP 10.152.183.115 <none> 9411/TCP,14250/TCP,14267/TCP,14268/TCP 13s
simplest-collector-headless ClusterIP None <none> 9411/TCP,14250/TCP,14267/TCP,14268/TCP 13s
simplest-query ClusterIP 10.152.183.123 <none> 16686/TCP 13s