My guess is that because you are appending it to a platform it will for some reason use default ordering. There might be a lot going on what you cannot see when you are directly manipulating JMP platforms like that. You could maybe use Clone Box to get the table and append to that (depending on what you are doing).
Names Default To Here(1);
dt = Open("$SAMPLE_DATA/Semiconductor Capability.jmp");
ps = dt << Process Screening(Grouping(:Site), Process Variables(Eval(5 :: 132)));
tb = Report(ps)[Table Box(1)];
delta = Matrix(Report(ps)[Number Col Box("Mean")] << get) - (Matrix(Report(ps)[Number Col Box("USL")] << get)
+ Matrix(Report(ps)[Number Col Box("LSL")] << get)) / 2;
scb4 = Number Col Edit Box("distance", delta);
nw = new window("",
tb1 = tb << Clone Box;
);
a = scb4 << get;
tb1 << append(scb4);
b = scb4 << get;
c2 = a - b;
scb4 = Number Col Edit Box("distance", delta);
a = scb4 << get;
tb << append(scb4);
b = scb4 << get;
c1 = a - b;
-Jarmo