The image cannot be rendered using v-for (the image has been src through the API)

problem description

the picture cannot be rendered using v-for (the picture has already been src through the API)
the environment background and what methods you have tried

related codes

<template>
<div class="recommend">
    <div class="recommend-content">
        <div class="slider-wrapper">
            <slider>
                <div v-for="item in recommends">
                    <a :href="item.linkUrl">
                        <img :src="item.picUrl"/>
                    </a>
                </div>
            </slider>
        </div>
        <div class="recommend-list">
            <h1 class="list-title"></h1>
        </div>
        <ul></ul>
    </div>
</div>
</template>

<script type="text/ecmascript-6">
import Slider from "base/slider/slider"
import {getRecommend} from "api/recommend"
import {ERR_OK} from "api/config"

export default {
  data () {
    return {
      recommends: []
    }
  },
  created () {
    this._getRecommend()
  },
  methods: {
    _getRecommend () {
      getRecommend().then((res) => {
        if (res.code === ERR_OK) {
          // console.log(res.data.slider)
          this.recommends = res.data.slider
        }
      })
    }
  },
  components: {
    Slider
  }
}

</script>

<style scoped lang="stylus" rel="stylesheet/stylus">
  @import "~common/stylus/variable"

  .recommend
    position: fixed
    width: 100%
    top: 88px
    bottom: 0
    .recommend-content
      height: 100%
      overflow: hidden
      .slider-wrapper
        position: relative
        width: 100%
        height: 0
        padding-top: 40%
        overflow: hidden
        .slider-content
          position: absolute
          top: 0
          left: 0
          width: 100%
          height: 100%
      .recommend-list
        .list-title
          height: 65px
          line-height: 65px
          text-align: center
          font-size: $font-size-medium
          color: $color-theme
        .item
          display: flex
          box-sizing: border-box
          align-items: center
          padding: 0 20px 20px 20px
          .icon
            flex: 0 0 60px
            width: 60px
            padding-right: 20px
          .text
            display: flex
            flex-direction: column
            justify-content: center
            flex: 1
            line-height: 20px
            overflow: hidden
            font-size: $font-size-medium
            .name
              margin-bottom: 10px
              color: $color-text
            .desc
              color: $color-text-d
      .loading-container
        position: absolute
        width: 100%
        top: 50%
        transform: translateY(-50%)
</style>

what result do you expect? What is the error message actually seen?

the console does not report an error message

Vue.js

Dec.08,2021