问题通过在度量中添加以下代码行来解决：

The issue was solved by adding following line of code to the measure:

Cumulative Quantity :=
    CALCULATE (
        SUM ( Transactions[Quantity] ),
        FILTER (
            ALL ( 'Date'[Date] ),
            'Date'[Date] <= MAX ( 'Date'[Date] )
        )
    )