Arelith

When a notebook is placed into a Book Bag (Enchanted), all weight reduction enchantments are stripped away along with the ownership of the item. Not sure if this also applies to all books, but it makes modifying descriptions of the notebooks harder due to a newly required re-enchantment.

This is because items going in/taken out aren't the exact same item. The scripts generate a new item by the blueprint and applies the name/description to them. The same thing occurs with fixtures.

Theoretically it's a bug but it's been the case for many years now, by this point I'd say it's intended if not already confirmed.

A quick fix for this is to place them inside a fixture: bookshelf. Then taking them out after. You'll be granted possession of them when you pull them out. Enabling you to redescribe/rename them afterwards. Or if you're rich and don't care about the coin, just enchant them with weight reductions. But really, public bookshelves are almost everywhere. And where you're writing, there's usually a bookshelf near those crafting stations.