If you're searching to filter all blank rows, you can do it with multiple filters easily. I used this formula (watch out the locale): =ARRAYFORMULA(FILTER(Sheet1!A2:A;Sheet1!C2:C="mysearch";Sheet1!B2:B<>""))
=ARRAYFORMULA(FILTER(Sheet1!A2:A;Sheet1!C2:C="mysearch";Sheet1!B2:B<>""))