Solved
CC's don't have thumbnails
After the latest game update, several of my cc's don't have thumbnails. They work but in the build menu, it's just empty. They're not specific to one creator or cc set.
Sometimes this is a DX9 vs. DX11 issue. You can run non-default CC through a Sims 4 Studio batch fix for this, or check if the creator has an update available. For default replacement CC, you'll need a creator update.
