I couldn't explain that to you, because that's not how it works for me. The mod works as intended for me. It sounds like you still have a mod conflict, though if you've got a workaround now it may not be worth your while to go through a whole 50/50 to find it.

Are any other items behaving in this way in your game? The problem may not be related to this specific mod at all, if so.

It's not a mod conflict (I ruled that out by running a barebones vanilla game - same problem). I think it's just some inexplicable weirdness specific to my game/setup/computer. And it is just, specifically, the custom novels. So if I have to use specific shelving to make the mod work, that's good enough FOR ME for now.

Edited to make my position absolutely, unmistakably crystal clear. Considering that I am running an old computer with an old, obsolete, no longer supported OS, with an old graphics card that only works with obsolete drivers, and that I'm also doing all kinds of other stuff on said computer besides just playing Sims2, it should be NO surprise if something is wonky and the problem can't be replicated by other people.

It's. Just. Me.