Cumulative calculation not returning data when no data for period selected

Hello,

I have some a table report where data is being displayed for the period selected (using date slider), and also cumulative data for each row groups. Cumulative calculation works fine except when there's no data for the period selected, as it should bring data from before the "From Date" in date slider.

So in the image above, we see cumulative data for Groups A,B and C. But when the slider date range selection is changed and there's no data for the period selected, the numbers disappear from the Cumulative columns like below (even though there's data that falls before the "From Date" in date slider:

Here's the formula I am using: 

Cumulative Tested = 
VAR _select=SELECTEDVALUE('vw_PRBI_Report_WeldRepairStats'[Project])
VAR _pStartDate = MINX(FILTER(ALL('vw_PRBI_Report_WeldRepairStats'),'vw_PRBI_Report_WeldRepairStats'[Project]=_select),[ProjectStartDate])
VAR _toDate=MAXX(ALLSELECTED('vw_PRBI_Report_WeldRepairStats'),'vw_PRBI_Report_WeldRepairStats'[TestedDate])
VAR __table = 
SUMMARIZE('vw_PRBI_Report_WeldRepairStats',[MaterialGroup],"__value",
    SUMX(
        FILTER(ALL('vw_PRBI_Report_WeldRepairStats'),
        'vw_PRBI_Report_WeldRepairStats'[TestedDate]>=_pStartDate && 
        'vw_PRBI_Report_WeldRepairStats'[TestedDate]<=_toDate &&
        'vw_PRBI_Report_WeldRepairStats'[Project]=_select && 
        'vw_PRBI_Report_WeldRepairStats'[MaterialGroup] = SELECTEDVALUE('vw_PRBI_Report_WeldRepairStats'[MaterialGroup]))
        ,ISBLANK([Tested]) || [Tested] = 0, 0, [Tested])
    )
)
RETURN
IF(
    HASONEVALUE(vw_PRBI_Report_WeldRepairStats[MaterialGroup]),
    SUMX(
        FILTER(ALL('vw_PRBI_Report_WeldRepairStats'),
        'vw_PRBI_Report_WeldRepairStats'[TestedDate]>=_pStartDate && 
        'vw_PRBI_Report_WeldRepairStats'[TestedDate]<=_toDate &&
        'vw_PRBI_Report_WeldRepairStats'[Project]=_select && 
        'vw_PRBI_Report_WeldRepairStats'[MaterialGroup] = SELECTEDVALUE('vw_PRBI_Report_WeldRepairStats'[MaterialGroup]))
        ,ISBLANK([Tested]) || [Tested] = 0, 0, [Tested])
    ),
    SUMX(__table,[__value])
)

@v-yangliu-msft helped me on the cumulative calculation and got ideas from Greg_Deckler's link  https://community.fabric.microsoft.com/t5/Quick-Measures-Gallery/Measure-Totals-The-Final-Word/m-p/547907  for displaying Cumulative totals in Total Row for this issue.

Thank you,

nhuda