Debian – MultiContainer with shared Volume as EmptyDir working however when used shared Volume as hostPath not working

I have K8s cluster with one master and one worker Node.
Scenario – 1 I am deploying a simple sidecar container within same POD where I have define emptyDir as share volume and it is working fine. The manifest file

apiVersion: apps/v1
kind: Deployment
metadata:
   name: pod-with-sidecar
   namespace: test
spec:
   replicas: 1
   selector:
     matchLabels:
         app: debian-nginx
   template:
      metadata:
        labels:
           app: debian-nginx
      spec:
        containers:
        - name: main-debian
          image: debian
          command: ["/bin/sh"]
          args: ["-c", "while true; do date >> /var/log/index.html; sleep 2;done"]
          volumeMounts:
          - mountPath: /var/log
            name: shared-log
        - name: sidecar-nginx
          image: nginx
          volumeMounts:
          - mountPath: /usr/share/nginx/index.html
            name: shared-log
        volumes:
         - name: shared-log
           emptyDir: {}  

Here
In Container – 1 the file is created and the content is available in /car/log/index.html
Similarly in Container – 2 the file is created and the content is available in usr/share/nginx/html/index.html

Scenario – 2 I am deploying same simple sidecar container within same POD where I have define hosPath as share volume and it is not working. The manifest file

apiVersion: apps/v1
kind: Deployment
metadata:
    name: pod-with-sidecar
    namespace: test
spec:
   replicas: 1
   selector:
     matchLabels:
         app: debian
         app: nginx
   template:
     metadata:
       labels:
          app: debian
          app: nginx
     spec:
       containers:
       # Main application container
       - name: main-debian
         image: debian
         command: ["/bin/sh", "-c"]
         args: ["while true; do data >> /var/log/index.html; sleep 2;done"]
         volumeMounts:
         - mountPath: /var/log
           name: shared-vol
       # Sidecar container
       - name: sidecar-nginx
         image: nginx:1.7.9
         ports:
         - containerPort: 80
         volumeMounts:
         - mountPath: /usr/share/nginx/html # nginx-specific mount path
           name: shared-vol
       volumes:
       - name: shared-vol
         hostPath:
           path: /mydata
           type: DirectoryOrCreate

Here

In Container – 1 the file is created but there is no content available in /car/log/index.html

testuser@kmasterl:~$ kubectl exec -it pod-with-sidecar-85f88c9d5d-xjcgh -c main-debian -n test -- /bin/bash 
root@pod-with-sidecar-85f88c9d5d-xjcgh:/# ls -lrt var/log 
total 0 -rw-r--r-- 1 root root 0 Dec 14 21:28 index.html 
root@pod-with-sidecar-85f88c9d5d-xjcgh:/# cat /var/log/index.html 
root@pod-with-sidecar-85f88c9d5d-xjcgh:/#

Similarly in Container – 2 the file is created but there is no content available in usr/share/nginx/html/index.html

testuser@kmasterl:~$ kubectl exec -it pod-with-sidecar-85f88c9d5d-xjcgh -c sidecar-nginx -n test -- /bin/bash 
root@pod-with-sidecar-85f88c9d5d-xjcgh:/# ls -lrt /usr/share/nginx/html 
total 0 -rw-r--r-- 1 root root 0 Dec 14 21:28 index.html 
root@pod-with-sidecar-85f88c9d5d-xjcgh:/# cat usr/share/nginx/html/index.html  
root@pod-with-sidecar-85f88c9d5d-xjcgh:/#  

Could anyone suggest why it is not working when hostPath is defined as shared volume??