Hard to tell without seeing sufficient code. Probable user error. :)
Using rng as you did will reset the seed. Thus we see:
rng(1234,'twister')
>> rand
ans =
0.19152
>> rand
ans =
0.62211
>> rng(1234,'twister')
>> rand
ans =
0.19152
So when I use rng again, the sequence repeats. Perhaps you are doing something along the line to interrupt that sequence, thus perhaps a rng('shuffle") is done somewhere, perhaps by some other code you are using, even something you may have downloaded. As I said, hard to know.
