It would be better if you describe exactly how did you experience the bug. Are you using automated or manual missions? Is your inventory full or close to full? If it's nearly or completely full when you run the missions, low-priority items such as books, junk and components might be left behind since there's no storage space available.
What I don't think you realize is that the permanent version of the Agriculture book (+50% water +50% food) is discontinued. In theory, you should not be able to loot it at all.
The 50% Agriculture book is not discontinued as far as I know, I'm pretty sure I looted one recently. You might be thinking of the A History Of Rationing book, which was discontinued on its higher permanent version (25%, 30% or something like that, I don't remember right now).
Also, you cannot view items you loot while in mission, only after. It seems a bit suspicious that you could tell what you looted.......
You can check the items you earned in the "Mission Completed" summary that opens just when your compound loads again or when your survivors return after an automated mission. Maybe he means that the book is in the summary, but when he goes to the inventory it's not there. It would be better if he could describe the issue more clearly to avoid confusion.
Edited by Lana Woo, 19 October 2017 - 04:05 PM.