Need help for dax dunction to count filter

HI xiumi_hou ,

I  think it should more be related to selectedvalue function, it will return blank when it returns multiple results, you can try to follow measure formula if it works: 

1st outreach outbound =
VAR BaseLineBaseDate =
    MIN ( Calls[date_start] )
RETURN
    CALCULATE (
        SELECTEDVALUE (
            Calls[Calls_cstm.channel_c],
            CONCATENATEX (
                VALUES ( Calls[Calls_cstm.channel_c] ),
                [Calls_cstm.channel_c],
                ","
            )
        ),
        FILTER (
            Calls,
            Calls[date_start] = BaseLineBaseDate
                && Calls[direction] = "Outbound"
        )
    )

Regards,

Xiaoxin Sheng