Is not keeping a picked up battle item a bug?

Greetings. l noticed something strange, and decided to make this post to ask if it was a bug or not.

I was battling a shuckle in Cyan Cavern, and after it used its berry juice, l switched in my phanpy, and it picked up the berry juice, as I intended (I saw on Serebii that “when a hold item is used in battle, if a Pokémon with PickUp doesn’t have a hold item, it will pick up that item.”) but when l exited the battle, phanpy no longer had the Berry Juice. I repeated this with my Meowth, and the same thing happened. It was there during the battle, but was gone when it ended.

So, is this a bug/oversight, or is it working as intended?