How to fetch field value via REST

Question

I am using Drupal 8. I have installed the Rest module. I need to do polling so I also installed the Poll module. I created two questions with choices in poll and after that I created a view to show polls in that view with Rest Export enabled.

Now there are 3 fields I am showing in my REST export:

• Question
• Choice
• PollID

currently I have two questions and their choices. Here is how its showing in JSON form.

     [{"question":"which is best city",
"choice_target_id":"Delhi, Mumbai, Chennai","id":"1"},
    {"question":"Where do you work?",
"choice_target_id":"Flat, Hotel, Factory, Shop","id":"2"}] 

But the thing is when I access the REST URL in my browser window where I am logged in it shows all the field as.

      [
{"question":"which is best city",
    "choice_target_id":"Delhi, Mumbai, Chennai","id":"1"},
    {"question":"Where do you work?",
    "choice_target_id":"Flat, Hotel, Factory, Shop","id":"2"}
] 

But when I am not login and when I then call the REST URL from Postman I get this:

[
    {
        "question": "which is best city",
        "choice_target_id": "",
        "id": "1"
    },
    {
        "question": "Where do you work?",
        "choice_target_id": "",
        "id": "2"
    }
]

choice_target_id is blank. What can be the reason of it?