TCPProbe annotations on pods didn't make pod probed

[MUCZ]

The tcpprobe seems to work well in the k3s cluster. It probes some sites continuously and I can see tcp-related metrics in the Prometheus and Grafana.
I follow the config file described in https://github.com/mehrdadrad/tcpprobe/wiki/helm , where i set a nginx deployment and annotate it to tell tcpprobe to "probe" it.
But after that I deployed the Nginx server. I found several things confusing.

• the annotation tcpprobe/targets: "http://PODIP:80" didn't get rewritten , which means that PODIP is literally PODIP and so i know the Nginx won't be "probed"
• even if i fill the right ip address of the nginx server using another pod's annotation, the Nginx server still didn't get probed. I see no data in the metrics it expose.

Env:
OS X + k3d cluster (k3s in docker)

I would appreciate all the help, thanks!

apiVersion: apps/v1 
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 1
  template:
    metadata:
      labels:
        app: nginx
      annotations:
        tcpprobe/targets: "http://PODIP:80"
        tcpprobe/interval: "10s"
        tcpprobe/labels: '{"app": "nginx"}'
    spec:
      containers:
        - name: nginx
          image: nginx:latest
          ports:
            - containerPort: 80