tooltip not working when markArea covered the whole chartecharts 折线配置项内容和展示

在markArea范围包含所有数据为什么tooltip不显示？

      function randomData() {
    now = new Date(+now + oneMinute);
    var fatigue = Math.random() * 2 - 1;
    return {
        value: [
            [now.getHours(), now.getMinutes()].join(":"),
            Math.round(fatigue * 100) / 100
        ]
    };
}

var now = +new Date();
var oneMinute = 60 * 1000;
var data = [];
var x = [];
for (var i = 0; i < 50; i++) {
    var item = randomData();
    data.push(item)
    x.push(item.value[0])
}

var option = {
    textStyle: {
        fontSize: 24
    },
    legend: {
      
        data:[{
           name: "Alert State",
           icon: "square",
           textStyle: {
              color: "#222222",
              fontSize: "13px",
              fontFamily: "Arial"
           }
        }]
    },
    tooltip: {
    	trigger: "axis",
    	formatter: function (params) {
    		console.log(params[0].value[0]);
            return params[0].value[0] + " / " + params[0].value[1];
        }
    },
    xAxis: {
        name: "Time Period",
        nameLocation: "middle",
        nameGap: "40",
        nameTextStyle: {
            fontSize: "16",
            fontWeight: "normal",
            fontStyle: "normal",
            fontFamily: "Arial"
        },
        data: x,
        axisLine: {
            show: false
        },
        axisTick: {
            show: false
        },
        splitLine: {
            show: false
        }
    },
    yAxis: {
        max: 'dataMax',
        min: 'dataMin',
        name: "Fatigue",
        nameTextStyle: {
            fontSize: "16",
            fontWeight: "normal",
            fontStyle: "normal",
            fontFamily: "Arial"
        },
        type: "value",
        axisLine: {
            show: false
        },
        axisTick: {
            show: false
        },
        splitLine: {
            show: true
        }
    },
    series: [{
        name: '模拟数据',
        type: 'line',
        showSymbol: false,
        hoverAnimation: false,
        data: data,
        itemStyle: {
            normal: {
                color: '#199CD8',
                borderColor: '#fff',
                borderWith: 1,
                shadowBlur: 2,
                shadowOffsetX: 2,
                shadowOffsetY: 5
            }
        },
        lineStyle: {
            normal: {
                width: 2,
                shadowColor: 'rgba(112, 155, 233, 0.5)',
                shadowBlur: 4,
                shadowOffsetY: 4
            }
        },
        markLine: {
            silent: true,
            symbol: false,
            animation: false,
            label: {
                normal: {
                    show: false
                }
            },
            data: [{
                yAxis: -0.10
            }],
            lineStyle: {
                normal: {
                    type: "solid",
                    color: "#CE1C08"
                }
            }
        },
        markArea: {
            itemStyle: {
                normal: {
                    color: "rgba(251,222,222,0.5)",
                    borderColor: "#CE1C08",
                    borderWith: 1
                }
            },
            data: [
                [{
                    // name: '两个屏幕坐标之间的标域',
                    yAxis:5
                }, {
                  //yAxis:0  //只要markArea不包含所有数据返回就能看见tooltip
                  //只要在markArea铺满屏幕时tooltip会不见
                    yAxis:-5 
                }]
            ]
        }
    }]
};

setInterval(function() {
    for (var j = 0; j < 5; j++) {
        var newitem = randomData();
        data.shift();
        data.push(newitem);
        x.shift();
        x.push(newitem.value[0]);
    }

    myChart.setOption({
        series: [{
            data: data
        }],
        xAxis: [{
            data: x
        }]
    });
}, 1000);