I want to open up a popup after axios response. alert and console.log is working but the popup is not working. it only works on a click event, computed and mounted methods

Questions
1 
      setInterval(function(){

             // APP CHECK
             axios.get('/api/v1/auth/check/app_block').then( response => {

             this.appBlock = response.data.active;
            // this.save_appBlock = localStorage.setItem('hsp_appBlock', this.appBlock);

             //alert('i am saying');

             if( this.appBlock == 0 ){

                 // GO TO APP BLOCK PAGE

                 //alert('Page is blocked');
                 this.testBlockPage = true;

                }else{

                 // alert('Page not blocked');
                  this.testBlockPage = false;
                }

             });


      }, 9000);