Items in off-hand slot can't be dropped with drop item key (default Q)

When you have items in your hotbar (1-9) you can drop items with Q without having to open the inventory, however if the item is in the off-hand slot and the main-hand is empty you can't drop it unless you press F to swap it to main-hand and then press Q.

Expected behavior would be that, if you have an item in your main-hand and in your off-hand slot, pressing Q would first drop the item in your selected slot and then pressing it again would drop the off-hand item.

How to reproduce

1. Have any item in your off-hand slot and in your main-hand.
2. Press the drop item key (Q).
3. Main-hand item drops.
4. Press it again.
5. Off-hand item can't be dropped.