I'm editing a piece of CAS CC someone else has created in S4S, but I can't seem to figure out change the swatch thumbnail (not the image, the color). It's simple to do for other CC, but for this one the solution eludes me...
Help would be appreciated, thanks <3

-Aq

What kind of CC is it?
If it's something unique to a recent pack, it's possible that S4S either hasn't been updated to display it properly or that functionality is only in the Open Beta version so far

it's a heterochromia facepaint for Aliens, made by Pralinesims. I also noticed that it doesn't let me delete swatches or CAS parts, which is frustrating because I don't have any desire to use to majority of the swatches. If i delete anything, save, and then reopen the file or go into the game all the swatches are still there. They just reappear. It allows me to override their textures with my own just fine, however.

this happens with other heterochromia cc I have as well.

Ahh, I think some older heterochromia CC can have these issues, I'm not sure what they got cloned from but it's difficult to work with. More recent CC of the same sort has improved, so I can think of a couple of options.

1. If you're comfortable potentially having to move around the placement of the texture to fit a new mesh, you could extract the swatches you want to keep as well as your custom ones and basically convert the CC to a newer mesh. You can check the packages of whatever CC you prefer, but for reference I know that Squea's Dynastid Hetereochromia doesn't have the issue as I've added my own swatches to it before.

2. S4PE definitely gets overshadowed by S4S for most things now, but it would have the advantage of skipping whatever is wrong with the interface for this item. You may be able to get a more literal view of the components of the package with S4PE and delete swatches and/or replace their colour codes manually.

How are you opening the file? With the My CC button or the My Projects button? Or are you just double clicking the package file?