[nickmarshallvfx]

I have had the same problem when creating starfields using Greg Martins technique as a base. No idea why it is, but it has me stumped too...
The technique seems to work fine at up to 1k resolution, but after that it just doesn't seem to work...
I had to do a 4k painting of a starfield recently, and found that if i scale the noise uo loads it seems to work. Try just scaling the noise up significantly when you are working. Sorry i cant offer anything more solid...

Nick