Ionic 4 ion-select is not opening select options

Ionic Framework
1

Im using ion-select in my page but when i click on select it will not showing option and then i cant click on input field also of other items . Also not opening the ion-select box to select the values.

<ion-content>

    <ion-item>
      <ion-label  position="floating" color="primary">Name</ion-label>
      <ion-input type="text"></ion-input>
    </ion-item>

    <ion-item>
      <ion-label  position="floating" color="primary">Phone Number</ion-label>
      <ion-input type="number"></ion-input>
    </ion-item>

    <ion-item>
      <ion-label  position="floating" color="primary">CNIC</ion-label>
      <ion-input type="number"></ion-input>
    </ion-item>

  <ion-item>
    <ion-label>Gender</ion-label>
    <ion-select placeholder="Select One">
    <ion-select-option value="f">Female</ion-select-option>
    <ion-select-option value="m">Male</ion-select-option>
   </ion-select>
   </ion-item>

</ion-content>

Is this is bug or any solution to fix it ?