=UNIQUE(QUERY({IMPORTRANGE("1xWx1FRfvCfmvYi9Sb7Gh5lIAb-NAt0RG0h-e_HKmxjU","APP Directory!A2:U");IMPORTRANGE("1xWx1FRfvCfmvYi9Sb7Gh5lIAb-NAt0RG0h-e_HKmxjU","APP Directory!A2:U")},"Select * Where Col1 is not null order by Col4 Asc",1))
This is what I get as an error:
Unable to parse query string for Function QUERY parameter 2: NO_COLUMN: Col4