In a new save, CC appears in the CAS catalouge.
In a new save, CC shows in Live mode and shows up in the avatar in the bottom left.
In a new save, there is only one CC item available in build mode.
All the CCs I downloaded have the proper meshes and are in the correct format. I also removed personal folders like "Eyebrows" and "Tops" so the files are just in the Mod folder.
Every old CC I've had in the game does not show up. With the tester sim in the game I've been playing in previously (not the new save), the original CC she had on was all gone so I went back into CAS. I replaced everything with new CC and it shows up in Live mode. But the "new CC" files were originally on my desktop, I didn't download new ones. All the old CCs that are gone in the world were files I've used since 2017. I do have a lot of CC but I make sure to put them in batches to test before I play. I had the Sims 4 Tray Importer downloaded and used that for a couple of years to find the broken CCs.
I used TwistedMexi's Better Expectations mod but I removed it and only have McCC in the folder. I also regularly updated the mods I used every time there was an update.
CAS cc is working fine with new saves, however, all my Build Mode cc is gone. I used to have a Furniture folder in my Mods but it is not there anymore. I never deleted it and I never took it out since it's not on my desktop. In-game, it says "# of build mode items were removed" and "# of cas items were removed" when I had the Better Exepections installed but it doesn't show up anymore.
I make sure to manually save in between if I play for a long time.