I’m not sure if this is a bug, but it’s definitely very annoying behavior that really ruins immersion.
First of all, Zois, even those without the “book lover” trait, continuously read. The problem is that if I direct them to do something else, they put the book in their bag instead of on the bookshelf, and they pull it back out between actions.
In the case of the photo, the child was reading, had the desire to kiss their mom, I selected that action, they put away the book for the duration of the action and then pulled it back out. As you can see, they don’t have the reading action queued, but they’re holding it in their hand and will keep putting it in and out of their bag between actions.
If they decide to read, they won’t use that book, but will pull out a different one from the bookshelf: I often find Zoi bags filled with several copies of the same book.
Often, though less frequently, the same thing happens with food.
When a Zoi stops reading, unless they’re away from home, they should put the book back on the bookshelf, unless I tell them to do otherwise.
I have frequently encountered the exact issue mentioned regarding item interactions. Specifically, placing books from the inventory back onto a bookshelf is an absolute ordeal. The character is strictly required to hold the book in their hands first; if the item is not currently held, the system invalidates the command. Only after the book is manually placed in the character’s hand does the “place on bookshelf” command function correctly.
Please consider this gameplay loop: characters constantly read books independently, but when their core needs deplete, the player must issue new commands to address them. In these instances, characters immediately stash the book they are holding directly into their inventory and proceed to execute the new command. Consequently, players eventually end up with dozens of books accumulated inside the inventory. To resolve this, the player is forced to micro-manage each book by forcing the character to hold it first and then commanding them to return it to the shelf. This is an incredibly tedious and inefficient user experience.
It’s not just the books, zois place drinks (from the drink mixer) and unfinished food dishes in their inventories. But the book thing is the worse. It’s like the “playing on a computer” that we used to have with The Sims. They just couldn’t help doing that action constantly. I mean, autonomy is always welcome, but not without purpose or direction. This infinite book reading is particularly annoying for me, cause I’m a serial game camera mod user and each time I go for a photo I get this message about needing the zoi to have empty hands to take it. I hope they fix this soon cause like it has already been said, it totally ruins the immersion! 
It’s exactly how you’ve described it too, and it’s one of the things that’s bothering me the most in the game right now.
I’m attaching a video where during a romantic date the book keeps disappearing and reappearing
Omg, this looks so annoying, I hope they fix it soon cause it interferes with important interactions and totally breaks the immersion. Plus, why of all the things zois could do autonomously would they choose to read books? Like, let them at least do something according to their traits or personality, or maybe to their careers? But every single zoi, not just those who are bookworms, constantly do this. Worse thing is sometimes they let those books scattered all over the floor. Please, make them stop!
