Vuetify vertical tabs

VerticalTabs.vue

<template>
    <div :style="containerStyle" class="vertical-tabs" :class="{'vertical-tabs--vertical-text': verticalText, 'vertical-tabs--horizontal-text': !verticalText}">
        <v-tabs :value="value" @input="$emit('input', $event)" :show-arrows="verticalText" :color="color" :slider-color="sliderColor" :style="tabsStyle">
            <v-tab v-for="item in items" :key="item">{{ item }}</v-tab>
        </v-tabs>
    </div>
</template>

<script>
  export default {
    name: 'vertical-tabs',

    props: {
      color: String,
      height: {
        type: [Number, String],
        default: 300,
      },
      items: Array,
      sliderColor: String,
      value: null,
      verticalText: Boolean,
    },

    computed: {
      containerStyle () {
        return this.verticalText ? {
          height: isNaN(this.height) ? this.height : `${this.height}px`,
        } : {
          height: (48 * this.items.length) + 'px',
        }
      },
      tabsStyle () {
        return this.verticalText ? {
          width: isNaN(this.height) ? this.height : `${this.height}px`,
        } : {}
      },
    },
  }
</script>

<style scoped>
    .vertical-tabs {
        overflow: hidden;
    }

    .vertical-tabs--horizontal-text .v-tabs {
        transform: rotate(90deg);
        transform-origin: 100px 100px;
        height: 200px;
    }

    .vertical-tabs--horizontal-text .v-tabs >>> .v-tabs__container {
        height: 200px;
    }

    .vertical-tabs--horizontal-text .v-tabs >>> .v-tabs__div {
        width: 48px;
        height: 200px;
        display: inline-block;
    }

    .vertical-tabs--horizontal-text .v-tabs >>> .v-tabs__item {
        transform: rotate(-90deg);
        transform-origin: 100px 100px;
        width: 200px;
        height: 48px;
        display: block;
        text-align: left;
        line-height: 36px;
        white-space: pre;
        overflow: hidden;
        text-overflow: ellipsis;
    }

    .vertical-tabs--vertical-text {
        width: 48px;
    }
    .vertical-tabs--vertical-text .v-tabs {
        transform: rotate(90deg);
        transform-origin: 24px 24px;
    }

    .vertical-tabs--vertical-text .v-tabs >>> .v-tabs__item {
        transform: rotate(180deg);
    }

    .vertical-tabs--vertical-text .v-tabs >>> .v-tabs__slider-wrapper {
        top: 0;
        bottom: auto;
    }
</style>

Hard to say without reproduction, did you pass items prop?