Help with my DAX formula

[Anonymous]

Hello!
So in the screenshot shown below I have two visuals. The left one is made using custom measures (which I will include) and the right one is just using Power BI. Some cells on the right visual appear empty but not on the left one. The left one seems to just copy the value of the non empty cell and put it in the empty one. Could someone please explain to me what's happening and pleease show me how to fix it? Thank you!

Visuals

Model

Measures

After Dialog Steps = 
var afterdate = MAX('Snapshot Date Info'[Date Time])
return
CALCULATE(
    SUMX(ST03N, [Number of Dialog Steps]),
    FILTER(
        ST03N,
        RELATED('Snapshot Date Info'[Date Time]) = afterdate
    )
)

Before Dialog Steps = 
var beforedate = MIN('Snapshot Date Info'[Date Time])
return
CALCULATE(
    SUMX(ST03N, [Number of Dialog Steps]),
    FILTER(
        ST03N,
        RELATED('Snapshot Date Info'[Date Time]) = beforedate
    )
)

[kentyler · Accepted solution]

Is there a reason you have a bi-drectional relationship between the tables ? This seems to be the kind of problem bidirectional relationships can cause.

[Anonymous]

@kentyler And you were right! I dont remember why I set it to bidirectional but yes that was a mistake. But why though, could you please explain to me a bit what the bidirectional selection did to cause that?

[kentyler]

Sorry

I am not fluent enough to explain exactly why. I just know it as a best practice. The Italians says "Using bi-directional relationships can lead to strange outcomes on reports, so don't use them unless you absolutely have to"..... so I try to follow the best practice...even though I might not understand the "complications"  https://www.sqlbi.com/articles/bidirectional-relationships-and-ambiguity-in-dax/