Several of the in-game posters and portraits:
Are not displaying custom recolors. It appears that these files are marked as 'not designable' in the legacy version of the game, when they have previously been designable in all other versions.
My guess, and this is just a guess, is that whoever made the CC made it with a game that includes IKEA. Even though they aren't directly related to the pack, they may still need it. A lot of people are encountering this with mods and CC. I'd suggest following the GitHub Legacy IKEA pack instructions to get that pack back in your game, then trying again.
I put IKEA back in my game before putting any CC or mods in and so far everything has worked fine.
I also actually figured this out - and felt really silly for doing so, but if you haven't got the Color Enable Package (CEP) then several items in game are just not designable. CEP is a mod and I've played with it so long that I forgot that that's what makes these objects designable (or recolorable). Updating for anyone else who's wondering - a LOT of in-game objects won't show recolors unless you have it!
