剑道Excel导出&rowSpan

我尝试使用kendo.ooxml.Workbook将数据导出到xlsx。它说我可以使用rowSpan，但似乎有问题。当我为A列和B列设置不同的行跨度时，C列中的最后两个单元格将消失：

var workbook = new kendo.ooxml.Workbook({
    sheets: [
        {
            rows: [
                {
                    cells: [
                        { value: "a", rowSpan: 3 },
                        { value: "b", rowSpan: 2 },
                        { value: "c"},
                        { value: "d"},
                    ]
                },
                {
                    cells: [
                        { value: "c"},
                        { value: "d"},
                    ]
                },
                {
                    cells: [
                        { value: "b", rowSpan: 4 },
                        { value: "c"},
                        { value: "d"},
                    ]
                },
                {
                    cells: [
                        { value: "a", rowSpan: 3 },
                        { value: "c"},
                        { value: "d"},
                    ]
                },
                {
                    cells: [
                        { value: "c"},
                        { value: "d"},
                    ]
                },
                {
                    cells: [
                        { value: "c"},
                        { value: "d"},
                    ]
                },
            ]
        }
    ]
});
kendo.saveAs({
    dataURI: workbook.toDataURL(),
    fileName: "Test.xlsx"
});

https://jsfiddle.net/92ggxnxn/

但是，如果我为A列和B列设置相同的行跨度，C列将包含所有值：

var workbook = new kendo.ooxml.Workbook({
    sheets: [
        {
            rows: [
                {
                    cells: [
                        { value: "a", rowSpan: 3 },
                        { value: "b", rowSpan: 3 },
                        { value: "c"},
                        { value: "d"},
                    ]
                },
                {
                    cells: [
                        { value: "c"},
                        { value: "d"},
                    ]
                },
                {
                    cells: [
                        { value: "c"},
                        { value: "d"},
                    ]
                },
                {
                    cells: [
                        { value: "a", rowSpan: 3 },
                        { value: "b", rowSpan: 3 },
                        { value: "c"},
                        { value: "d"},
                    ]
                },
                {
                    cells: [
                        { value: "c"},
                        { value: "d"},
                    ]
                },
                {
                    cells: [
                        { value: "c"},
                        { value: "d"},
                    ]
                },
            ]
        }
    ]
});
kendo.saveAs({
    dataURI: workbook.toDataURL(),
    fileName: "Test.xlsx"
});

https://jsfiddle.net/pb349fx2/

这是一个bug，还是我做错了什么？