SAP BW App Server - Variable not passed back to Server

Dear Power BI Community,

we've been struggling to set up a Power BI - SAP Connection for weeks now, always running into new issues.

The newest one is the following:

To reduce the amount of data to be extracted, the SAP admin has defined a variable (Load Date) that has to be passed, so not all dates will be loaded into the PBI data model.

However, no matter what we try, the SAP server always returns the full dataset, although I have cleary chosen the data to be restricted. Please find below a screenshot and the M Code behind it.

Has anyone of you had such a problem and was able to solve it?

Best regards from Germany!

 

let
    Source = SapBusinessWarehouse.Cubes("XXX", "XX", "XXX", [Implementation="2.0"]),
    PC1S1M = Source{[Name="PC1S1M"]}[Data],
    #"PC1S1M/N1S0_PC1S1M_001" = PC1S1M{[Id="PC1S1M/N1S0_PC1S1M_001"]}[Data],
    #"Added Items" = Cube.Transform(#"PC1S1M/N1S0_PC1S1M_001",
        {
            {Cube.ApplyParameter, "[0I_DAYS]", {"[4PC1S1M-LOAD_DATE].[20200420]", "[4PC1S1M-LOAD_DATE].[20200423]"}},
            {Cube.AddAndExpandDimensionColumn, "[4PC1S1M-LOAD_DATE]", {"[4PC1S1M-LOAD_DATE].[LEVEL01]"}, {"LOAD_DATE.LOAD_DATE Stufe 01"}},
            {Table.AddColumn, "LOAD_DATE.LOAD_DATE Stufe 01.LOAD_DATE Stufe 01.UniqueName", each Cube.AttributeMemberProperty([LOAD_DATE.LOAD_DATE Stufe 01], "[MEMBER_UNIQUE_NAME]")}
        })
in
    #"Added Items"