4012 is problematic, that why they’ve now updated their range to only 4011 and 4013. Once stock of 4012 runs out it’s done.
are you using Createx airbrush Colors opaque or Createx Wixked opaque ?
the 2nd photo looks more lumpy than separated, get a skewer and give the paint a good stir to get the thick stuff off the bottom, put the lid back on and give it a good shake, use some women’s nylons over the top when you add it to the cup to strain out the lumps.
Is it possible your paint may have been frozen