【报Bug】2.8.1 nvue界面中cover-view 无法覆盖video

示例代码：

nvue界面

<template>  
    <div>  
        <video id='video1' class="video" src="https://vdept.bdstatic.com/6e474b344d6e414c42734258385a6632/4372374e74387452/eb5f0aaf26c61ca2fb3fad28649207e14b2e0e118de4f6e68228c27510277d44e16ff72f6b8cd7db5717a3a56d94bf2cb1815a50f86a8b43451d75ee4a87daf7.mp4?auth_key=1595480349-0-0-00f1f554b3d12827bbaa870b1feafb59" autoplay="false" duration="" controls="true" :danmu-list="list"  
            danmu-btn="true" enable-danmu="true" :loop="true" muted="true" initial-time="" direction="-90"  
            show-mute-btn="true" @play="onstart" @pause="onpause" @ended="onfinish" @error="onfail" @waiting="waiting"  
            @timeupdate="timeupdate" @fullscreenchange="fullscreenchange">  

            <cover-view class="cover">  
                <h1>hahahahahha</h1>  
                <h1>hahahahahha</h1>  
                <h1>hahahahahha</h1>  
                <h1>hahahahahha</h1>  
                <h1>hahahahahha</h1>  
                <h1>hahahahahha</h1>   
            </cover-view>  
            </video>  
        <button class="btn" @click="play">播放</button>  
        <button class="btn" @click="pause">暂停</button>  
        <button class="btn" @click="seek">跳转到指定位置</button>  
        <button class="btn" @click="stop">停止</button>  
        <button class="btn" @click="fullScreen">全屏</button>  
        <button class="btn" @click="exitFullScreen">退出全屏</button>  
        <button class="btn" @click="playbackRate">设置倍速</button>  
        <button class="btn" @click="sendDanmu">发送弹幕</button>  
    </div>  
</template>  

<script>  
    export default {  
        data: {  
            src: "https://img.cdn.aliyun.dcloud.net.cn/guide/uniapp/%E7%AC%AC1%E8%AE%B2%EF%BC%88uni-app%E4%BA%A7%E5%93%81%E4%BB%8B%E7%BB%8D%EF%BC%89-%20DCloud%E5%AE%98%E6%96%B9%E8%A7%86%E9%A2%91%E6%95%99%E7%A8%8B@20181126-lite.m4v",  
            fil: true,  
            list: [{  
                text: '哈哈哈',  
                color: '#FF0000',  
                time: 2  
            }]  
        },  
        onReady() {  
            this.context = uni.createVideoContext("video1", this);  
        },  
        methods: {  
            onstart(e) {  
                console.log("onstart:" + JSON.stringify(e));  
            },  
            onpause(e) {  
                console.log("onpause:" + JSON.stringify(e));  
            },  
            onfinish(e) {  
                console.log("onfinish:" + JSON.stringify(e));  
            },  
            onfail(e) {  
                console.log("onfail:" + JSON.stringify(e));  
            },  
            fullscreenchange(e) {  
                console.log("fullscreenchange:" + JSON.stringify(e));  
            },  
            waiting(e) {  
                console.log("waiting:" + JSON.stringify(e));  
            },  
            timeupdate(e) {  
                console.log("timeupdate:" + JSON.stringify(e));  
            },  

            play() {  
                this.context.play();  
            },  
            pause() {  
                this.context.pause();  
            },  
            seek() {  
                this.context.seek(20);  
            },  
            stop() {  
                this.context.stop();  
            },  
            fullScreen() {  
                this.context.requestFullScreen({  
                    direction: 90  
                });  
            },  
            exitFullScreen() {  
                this.context.exitFullScreen();  
            },  
            sendDanmu() {  
                this.context.sendDanmu({  
                    text: '哈哈哈',  
                    color: '#FF0000'  
                });  
            },  
            playbackRate() {  
                this.context.playbackRate(2);  
            }  
        }  
    }  
</script>  

<style>  
    .video {  
        width: 750rpx;  
        height: 400rpx;  
        background-color: #808080;  
    }  

    .btn {  
        margin-top: 5px;  
        margin-bottom: 5px;  
        ;  
    }  
    .cover{  
        position: absolute;  

    }  
</style>  

操作步骤：

nvue界面中cover-view 无法覆盖video

预期结果：

覆盖video

实际结果：

nvue界面中cover-view 无法覆盖video