Inconsistent behavior for '= null' conditions on static columns

create table txtable(pcol bigint, ccol bigint, scol bigint static, ncol text, primary key((pcol), ccol));

begin batch
    insert into txtable (pcol, ccol, ncol) values (1, 1, 'A');
    update txtable set scol = 1 where pcol = 1 if scol = null;
apply batch;

[applied]
-----------
     False

insert into txtable (pcol, scol) values (1, null) if not exists;

begin batch
    insert into txtable (pcol, ccol, ncol) values (1, 1, 'A');
    update txtable set scol = 1 where pcol = 1 if scol = null;
apply batch;

[applied]
-----------
     True