Thanks, there must be something broken with the random number generator. I'll look at it.
When called from a script, the Shuffle function doesn't take any arguments so it will be limited to whatever the ShuffleMode=Random parameter does, which is what's broken.
It would be cool though if script Shuffle offered you more control, like pattens:
Shuffle(1,3,2,3,4,3,1,1)
or randoms
Shuffle(rand(1 4) rand(2 4) rand(3 4) 4)