I would not be surprised if the 5.2 Stabilizer addition was your problem. It should actually be called 5.8 stabilizer since that is where both AJ Delange and Kai Troester have found that it tends to put the mash pH. It is not a good addition to brewing and it also adds a substantial sodium content to your wort. A 5.8 mash pH can cause problems.
If your water is alkaline, you would be better served by learning to use acid for pH control.
But a 5.8 pH mash would cause astringency, too, and we've eliminated that as a cause. Likewise, no off-flavors due to metallic notes, so we can eliminate that as a haze former.
I'm also not convinced that cold break is the problem, since this is a new problem and Skyler's had good results with his system so far. Anyhow, it's my experience that cold break tends to drop out of solution reasonably well, and excess cold break is more of a storage problem than a haze former.
I think it's a grain problem. Either poor crush or mash problems resulted in incomplete conversion and that threw a starch haze. Protein haze is another possibility. In Gordon Strong's new book, he says that some malts, even identical malts from different maltsters, sometimes need a protein mash at 131 F for 15? minutes in order to get good clarity. While Great Western malt might work well for most brewers, oddities with Skyler's water and/or system might mean that it doesn't work so well for him. I haven't had this problem on my system and I haven't used GW malt, so I'm guessing, though.
How about body and head formation and retention? Is the beer a bit chewier than you'd expect? Did you notice it having unusually high or low foam during krausen? Are you getting any doughy, floury or "worty" notes from your malt?
As for using acids to adjust your pH, generally 1-3 tablespoons of food grade lactic or phosphoric acid per 5 gallons of water will do it, based on mineral profile of your water and grist. Take a sample of your cold brewing liquor, carefully add your acid drop by drop (and eye dropper works well, figure about 1 ml per drop) and test pH using good-quality pH strips or a pH tester as you go along. Since your mash pH will drop at conversion temperatures, subtract 0.4 pH to get your true mash pH. Once you've got your mash pH adjusted, you can convert units and scale up to apply the correct amount of acid to all your brewing liquor (mash and sparge). Don't sweat it too much, though, you just need to be in the ballpark - 5.2-5.6 pH.
I think it's much more critical to monitor pH during runoff. Anything above about 5.7 pH and you start getting tannins, which is a sure road to misery.