Improper Aggregation based on Slicer Selection (Descending Cumulative Total)

Hello Experts,

I'm quite confused. I have calculated a descending running total like so:

DescendingCumulativeSum = 
VAR MaxDate = MAX('Patent List'[Earliest Priority Date])
VAR TotalCount = COUNTROWS(
    FILTER(
        ALL('Patent List'),
        'Patent List'[Dead or Alive] = "DEAD" &&
        'Patent List'[ExpiredPatentCountCategory] <> Blank()
    )
)
RETURN
    TotalCount - 
    CALCULATE(
        COUNTROWS('Patent List'),
        FILTER(
            ALL('Patent List'),
            'Patent List'[Earliest Priority Date] <= MaxDate &&
            'Patent List'[Dead or Alive] = "DEAD" &&
            'Patent List'[ExpiredPatentCountCategory] <> Blank()
        )
    ) + [_ExpiredCount]

 This seems okay and I get my expected output:

So, what I'd like to do is give the user optionality to filter between Assignee Companies. If I create a slicer for this, it works.... but only if I select a single company. Selecting two or more companies creates some weird aggregation.

To combat, I added a VALUES clause, as I thought that might alleviate the issue. No dice.

DescendingCumulativeSum_Select = 
VAR CurrentDate = MAX('Patent List'[Earliest Priority Date])
VAR SelectedCompanies = VALUES('Patent List'[Assignee Company])
VAR TotalCount = COUNTROWS(
    FILTER(
        ALL('Patent List'),
        'Patent List'[Dead or Alive] = "DEAD" &&
        'Patent List'[ExpiredPatentCountCategory] <> BLANK() &&
        'Patent List'[Assignee Company] IN SelectedCompanies
    )
)
RETURN
    TotalCount - 
    CALCULATE(
        COUNTROWS('Patent List'),
        FILTER(
            ALL('Patent List'),
            'Patent List'[Earliest Priority Date] <= CurrentDate &&
            'Patent List'[Dead or Alive] = "DEAD" &&
            'Patent List'[ExpiredPatentCountCategory] <> BLANK() &&
            'Patent List'[Assignee Company] IN SelectedCompanies
        )
    ) + [_ExpiredCount]

However, if I hard-code the company name into the logic then it works.

DescendingCumulativeSum_Specific = 
VAR CurrentDate = MAX('Patent List'[Earliest Priority Date])
VAR TotalCount = COUNTROWS(
    FILTER(
        ALL('Patent List'),
        'Patent List'[Dead or Alive] = "DEAD" &&
        'Patent List'[ExpiredPatentCountCategory] <> BLANK() &&
        'Patent List'[Assignee Company] IN {"Hitachi Metals", "TDK", "Shin-Etsu"}
    )
)
RETURN
    TotalCount - 
    CALCULATE(
        COUNTROWS('Patent List'),
        FILTER(
            ALL('Patent List'),
            'Patent List'[Earliest Priority Date] <= CurrentDate &&
            'Patent List'[Dead or Alive] = "DEAD" &&
            'Patent List'[ExpiredPatentCountCategory] <> BLANK() &&
            'Patent List'[Assignee Company] IN {"Hitachi Metals", "TDK", "Shin-Etsu"}
        )
    ) + [_CountSpecific]

The red is DescendingCumultiaveSum_Select, while the green is DescendingCumulativeSum_Specific. 

Can someone help me understand what is happening here? Hoping I am overlooking something obvious. 

Thank you!