Hi!, I'm not sure what the problem is, the foals appear to have the genes you selected for them and they are displaying correctly. Is it the adult previews that are wrong? could you show me what the adult previews of your foals look like? 

i think it's the foal sabino layers, in the images the foals in the design lab are not showing their sabino layers but are showing them after being created.

the reason is because the design lab works somewhat differently with layering. there is only one layer per pattern for foals but multiple variations for adults. if you select a pattern variation on an adult horse in the lab, then switch to a foal, the lab will try to load a "foal variation" and be unable to which breaks the image. so with a sabino variation on the adult, the foal won't show sabino in the design lab but when you actually create the foal the sabino layer will show up correctly.

The only real way to know is to preview them as adults from their pages

Thanks guys! I had no idea you could preview them as an adult. I did some searching and found it. It shows the correct custom coloring I originally created once they are an adult! So should be fine :D