Single player
No mods
2.3 (10.02.2021)
The new light-weight arrows cannot be loaded to a bow or fired.
They can be used. Place them on your hotbar, equip the bow, press on the arrow and shoot. Watch the number of your arrows go down.
However, it is correct that you can’t drag them on the bow to equip them.
That sounds like a feature to me :^)
You need to equip the arrows to use them.