Outer set analysis - direct expression vs master measure item

[fabrice_lattern]

Hello,

I am encountering a strange behavior while using outer set analysis + master item measure compared to the direct writing of the same expression without using master measure.

Here is the definition of my master measure item, called [Responses YTD] : 

COUNT(distinct 
{<$(vYTDModifier), 
[Contact Survey invite status] = {'Responded'}, 
[Main contact survey response] = {'Yes'}, 
[Contact survey status 2] = {'5-Distributed'},
[Survey response submit date] = {"<=$(=Max(Date([Survey response closing date])))"}>} [Contact survey ID])

The vYTDModifier variable contains the following code, and is intented to ignore user selections on calendar table, to force YTD :

Date=,Month=,MonthName=,Period=,Quarter=,[Seq_Périod]=,YearQuarter=,Year = {"$(=Max(Year))"}, MonthNum = {">=1<=$(=Max(MonthNum))"}

Now I get different result when I write this two expressions :

Expression 1 (outer set + master measure)

{<[Survey type] = {'Field Service Intervention'}, [Sub-Region] = {'MEA'}>}[Responses YTD]

Expression 2 (copy paste of the definition of the master measure in place of the master measure)

{<[Survey type] = {'Field Service Intervention'}, [Sub-Region] = {'MEA'}>}
COUNT(distinct {<
$(vYTDModifier), 
[Contact Survey invite status] = {'Responded'}, [
Main contact survey response] = {'Yes'}, 
[Contact survey status 2] = {'5-Distributed'},
[Survey response submit date] = {"<=$(=Max(Date([Survey response closing date])))"}>} [Contact survey ID])

In terms of data, we have 4 surveys corresponding to the definition in march, 1 in april, 0 in may. 

When user selects march : results matches (4)
When user selects april : results matches (4+1 = 5)
When user selects may : expression 1 return 0, expression 2 return the correct response, 5.

Did I miss something on the way the master measure items are working ? It feels like when no data is corresponding to the user selection + outer set, it is not working even if user selections should be ignored in the inner set. 

We are running QlikSense on premise, with the version of february 2023 patch 5.