Material invisible options on multiple select

Question

I made a select in vue2, but as I scroll the fields, sometimes it appears, sometimes not. I couldn't find what to do?

   <div class="md-layout-item">
            <md-field class="condensed-field">
              <label for="test">Test</label>
              <md-select v-model="selectedTest" name="test" id="test" multiple>
                <md-option v-for="value in Values" :key="value.id" :value="value.name">{{value.name}}</md-option>
              </md-select>
            </md-field>
          </div>