Ng-fullcalendar event timeline issue

Hello. Im having issue with ng-fullcalendar.

As you can see, start time is correct but end time is not showing well.

Ionic:

   ionic (Ionic CLI)  : 4.12.0 (/Users/pc-areaindustries/.npm-global/lib/node_modules/ionic)
   Ionic Framework    : ionic-angular 3.9.2
   @ionic/app-scripts : 3.2.3

Cordova:

   cordova (Cordova CLI) : 7.1.0
   Cordova Platforms     : android 7.1.4
   Cordova Plugins       : cordova-plugin-ionic-keyboard 2.2.0, cordova-plugin-ionic-webview 4.0.0, (and 21 other plugins)

System:

   Android SDK Tools : 26.1.1 (/Users/pc-areaindustries/Library/Android/sdk)
   NodeJS            : v8.16.2 (/Users/pc-areaindustries/.nvm/versions/node/v8.16.2/bin/node)
   npm               : 6.4.1
   OS                : macOS

package.json

"ng-fullcalendar": "^1.7.5",
"fullcalendar": "^3.6.2",

HTML

<ng-fullcalendar #ucCalendar [options]="calendarOptions" (eventClick)="eventClick($event.detail)"></ng-fullcalendar>

TS

this.calendarOptions = {
        defaultView: 'agendaDay',
        minTime: duration("06:00:00"),
        maxTime: duration("22:00:00"),
        contentHeight: 700,
        themeSystem: "standard",
        header: false,
        buttonText: {
          today: 'Oggi',
          month: 'Mese',
          week: 'Settimana',
          day: 'Giorno',
          list: 'Agenda'
        },

        allDayText: 'Tutto il giorno',
        slotLabelFormat: 'HH:mm',
        timeFormat: 'h:mm',
        // header: {
        //   left: 'prev,next today',
        //   center: 'title',
        //   right: 'month,agendaWeek,agendaDay,listWeek'
        // },
        // locale: "it",
        navLinks: false, // can click day/week names to navigate views
        editable: false,
        selectable: true,
        eventLimit: false, // allow "more" link when too many events
        events: [
          {
            "start": "2020-12-28 09:00:00",
            "end": "2020-12-28 13:00:00",
            "title": "DIANA CIPRIANO Trasporto e Montaggio  ",
            "color": "#008000",
            "recapito": "TRAVERSA VIII CORSO EUROPA ",
            "citta": "Casapesenna",
            "telefono": "3881172040",
            "id": 1
          },
          {
            "start": "2020-12-28 14:00:00",
            "end": "2020-12-28 16:00:00",
            "title": "NETTI MARCO RITIRO MERCE DA CLIENTE",
            // "color": "#E5E5E5",
            "recapito": "VIA DOMIZIANA KM 36.00",
            "citta": "CASTEL VOLTURNO",
            "telefono": "0815093922",
            "id": 2
          }
        ]
         //JSON.stringify(this.pianificazioneMensile()),

      }