Filter context not working as expected

Hi all, I have a table with customers IDs, and their first, second and third car purchase dates. With the below formula, what I am trying to do is at any given date, calculate the number of customers, who has ONLY two cars. It is basically count of customers who have purchased their first car, and not yet their second car (So the date should be greater than their first car purchase date and less than their second car purchase date.) This all works fine without any relationship. However when I create a relationship with another table based on customer ID, then somehow the filter context applies, and my numbers are messed up (It has to do something with the dates). Would anyone know how can I rectify this formula to accommodate relationships? It feels like I should put an allexcept somewhere in the formula but I could not figure it out

Two_cars_customers_count =
VAR tmpEff = ADDCOLUMNS('Device PURCHASE data',"Effective Date",IF(ISBLANK([THIRD_PURCHASE_DATE]),TODAY(),[THIRD_PURCHASE_DATE]))
VAR tmpTable =  
SELECTCOLUMNS(
    FILTER(
        GENERATE(
            tmpEff,
            'Date_Lookup'
        ),
        [Date] >= [SECOND_PURCHASE_DATE] &&
        [Date] < [Effective Date] &&
        [SECOND_PURCHASE_DATE]<> BLANK()
    ),
    "ID",[Customer_ID],
    "Date",[Date]
)
VAR tmpTable1 = GROUPBY(tmpTable,[ID],"Count",COUNTX(CURRENTGROUP(),[Date]))
RETURN  IF(ISBLANK(COUNTROWS(tmpTable1)),0, COUNTROWS(tmpTable1) )

Screenshot of my graph without any relationship (Working as expected)

I am putting the below relationship

Now my graph looks like this (Not expected), most likely due to context filter. (I did not change anything else)