v-model is not working on dynamic radio buttons, vue js - vue.js

Question

var vue = new Vue({
el: '#app',
data: function (){
return {
categories: null,
foodItems: null,
selectedCategoryId: null
}
},
mounted: function() {
axios
.get('#Url.Action("GetCategories", "Home", new { area="Canteen" })')
.then(response => (this.categories = response.data))
}
});
<span>selected: {{ selectedCategoryId }}</span>
<div class="box box-default">
<div class="box-header with-border">
<div class="text-center text-uppercase"><b>Select</b></div>
</div>
<div class="box-body">
<div class="btn-group-vertical btn-block btn-group-toggle" data-toggle="buttons">
<label v-for="(category, index) in categories" class="btn btn-default active">
<input :id="'option-' + category.id" :value="category.id" type="radio" name="categories" autocomplete="off" v-model="selectedCategoryId" />{{ category.name }}
</label>
</div>
</div>
</div>

Answer 1

Here is working example
var vue = new Vue({
el: '#app',
data: function (){
return {
categories: null,
foodItems: null,
selectedCategoryId: null,
isdata:false
}
},
mounted: function() {
console.log("mounted");
var vm = this;
setTimeout(function(){
vm.categories = [
{id:1,name:'test1'},
{id:2,name:'test2'},
{id:3,name:'test3'}
];
vm.isdata = true;
}, 2000);
}
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.16/vue.js"></script>
<div id="app">
<span>selected: {{ selectedCategoryId }}</span>
<div class="box box-default">
<div class="box-header with-border">
<div v-show="!isdata">Loading....</div>
<div v-show="isdata" class="text-center text-uppercase"><b>Select</b></div>
</div>
<div class="box-body">
<div class="btn-group-vertical btn-block btn-group-toggle" data-toggle="buttons">
<label v-for="(category, index) in categories" class="btn btn-default active">
<input :id="'option-' + category.id" :value="category.id" type="radio" name="categories" autocomplete="off" v-model="selectedCategoryId" />{{ category.name }}
</label>
</div>
</div>
</div>
</div>