Visual Filter for Cumulative Sum Issue

AnonymousUpdate cummulative total DAX as give below and that will do it, as Seward12533 suggested to use cross filter to both direction, it has performance hit but instead of setting up the relationship, you can use it in DAX formula basically you are using cross filter to both direction when required

Cumulative = 
CALCULATE(
SUM('Table2'[Count]),
CROSSFILTER(Table1[Week of Year],Table2[Week No.], Both),
FILTER(ALL('Table2'),
'Table2'[Week No.]<=MAX('Table2'[Week No.]))
)

 

Anonymous try this

Cumulative = VAR Result = 
CALCULATE(
SUM('Table2'[Count]),
CROSSFILTER(Table1[Week of Year],Table2[Week No.], Both),
FILTER(ALL('Table2'),
'Table2'[Week No.]<=MAX('Table2'[Week No.]))
)
RETURN
IF(Result,Result,0)