Swatch thumbnails white in game

I've created a pants recolor. I've done this dozens of times with no issue. All the swatches are black and white. In S4S they look correct but in game, the swatches are all white. I've tried deleting the localthumbnailcache before moving the file back into my mods folder but that didn't seem to fix my issue. Does anyone know how to fix this so the swatch thumbnails show up as black and white?

Edit: Forgot to add I'm using the most current version of S4S. I'm not importing swatch thumbnails, just using the colors available in the program. I do have a custom thumbnail for CAS, created in photoshop.