Detect Past Month lost customer

Hey APR92, there is probably a much cleaner way to do this, but try this:

Lost2 = 
VAR selectedDate =
    SELECTEDVALUE(Consulta1[Date])
VAR selectedCategory =
    SELECTEDVALUE(Consulta1[Category])
VAR tbl =
    ADDCOLUMNS (
        ADDCOLUMNS (
            Consulta1,
            "Active Last Month",
                MAXX (
                    FILTER (
                        ALL ( Consulta1 ),
                        Consulta1[Date] < EARLIER(Consulta1[Date])
                            && (
                                Consulta1[Category] = EARLIER(Consulta1[Category])
                                    || ISBLANK ( EARLIER(Consulta1[Category]) )
                            )
                    ),
                    Consulta1[Active]
                )
        ),
        "Lost",
            SWITCH (
                TRUE,
                ISBLANK ( [Active Last Month] ), BLANK (),
                [Active Last Month] < Consulta1[Active], 0,
                [Active Last Month] - Consulta1[Active]
            )
    )
VAR lost = 
    SUMX (
        FILTER (
            tbl,
            Consulta1[Date] = selectedDate
                && (
                    Consulta1[Category] = selectedCategory
                        || ISBLANK ( selectedCategory )
                )
        ),
        [Lost]
    )
RETURN lost