DAX add 0 will happen cartesian product

[Joyceshen123456]

There are table1[YM] and table2[YM,amount]，and they relationship is table1[YM] ---> table2[YM],

and make a dax -->   

amount_1 = SUM(t2[Amount])+0

amount 2 = SUM(t2[Amount])

when I drag table1[YM] 、 table2[YM] columns and [amount 2] , the table is correct

but when I drag [amount 1] ， the Table display wrong

so I want to know why does this display occur，is it a debug?

[Greg_Deckler]

@Joyceshen123456 It's not a bug. Table and matrix visuals do not display don't display rows when values come back blank. The rows you are seeing in the last image are still present and in context, it's just that they are suppressed above because only the 202302 row has an amount 2 result that is non-blank. However, in once you force a +0, then all rows return a non-blank value.

[Joyceshen123456]

Thank you very much for answering my question，I still feel confused about that the t1 and t2 tables have a one-to-many relationship by [YM] ，so in the table the first column is t1[YM], the Second is t2[YM],so when the dax+0, it look like the one-to-many relationship is disable？（if i use sql,t1 left join t2,it only have one line,those data with 0 will not be displayed）