When you have something in your action bar and want to use it by right clicking in the inventory, it sometimes says "you are already using something" until you take that item into your hands, thenn it uses it automatically.
- Legacy ID
Is easy to reproduce.
Take a drink into your action bar. take something else in your hands. right click drink the drink. then it should show "already using someting" until u take drink in hands.
maybe its only when you already drank something else before im not sure.