OK, this is getting tough 🙂

Are any of the parameters marked as Sensitive?

Can you confirm from the All Executions reports that the values of the parameters...

Please expand on the above.

Hmm, OK.
Where, exactly, are you seeing this message?

Try something like this

BEGIN TRY
    IF NOT EXISTS (
            SELECT 1
            FROM dbo.view_MyView
            WHERE MemberID = @MemberID
            )
    BEGIN
        THROW 50000
            ,'MemberId does not exist'
            ,1;