I had 60 potatoes, 3 diamond axes, and an Efficiency IV Projectile Protection IV Luck of the Sea III enchant book in my inventory. I went through the spawn portal into the town portal building. I then moved the enchant book from 1 slot in my inventory to another and now it is gone.

I would like to add a second occurrence that struck a few minutes ago. I took a stack of 64 torches and moved it to hand 3. I placed one torch, it vanished and so did the other 63.