Trading with Villagers Removes Right Hand Item

I held an item in my right hand while trading with a villager. After completing a trade, the item was gone. I was also holding something in my off-hand, but it remained unscathed. Closing and opening the world did not restore the missing item. I have not tried trading with an item in my right hand but not left.
I am playing on Realms, as the admin with op privileges.