CC wallpapers affected by 9/18 patch?

I just patched my game, and while most seems to work fine, I noticed some problems with a few custom wallpapers. I never expected wallpapers to be a problem, as I thought they had rather simple tech features, and also that they all were created the same way technically.

Some of them show the blue/red with a big question mark on. I've seen something similar before on CC clothing, and think it refers to missing swatch. However, the same wall paper can now work in one room, but not in another room upstairs. Because the two floors have different wall height, I though maybe there was some minor tech upgrade related to missing swatch for a certain height. I thought the wall would then just not appear in the B/B catalog, but in this case it was already on the wall and working fine prior to the patch.

I also noticed that when pointing on the wall in an  affected room, the outer wall would vanish for a blink of a second, then restore back to normal. This did nit happen for rooms with working wallpaper. When I replaced the question mark walls, the vanishing stopped for that room.

Has this anything to do with DirectX? I just noticed, much to my surprise, that my game had launched DirectX 11.1 although my old computer with integrated vid card is lagging already. Because of the vanishing of walls, could my problem relate to DirectX 11.1?

I just don't understand how a patch can make some CC walls invalid, while other CC walls are fine. Can other objects in that room make a difference? Like light sources or animated objects (fire place etc)?

Any thoughts?

PS: I did remove Mods when patching, and have put it all back in. Hard testing CC walls without adding the files, but I did not search for other CC objects affecting the walls - no idea how that would even be possible for them to do so?