The bug
24w44a fixed MC-177084. However, while the subtitles appear when using playsound to play the associated sound event, the subtitle does not appear in practice when flying.
How to reproduce
Equip an elytra and start gliding
/playsound minecraft:item.elytra.flying
Expected results
In both cases, the new subtitle would be displayed.
Actual results
It plays with the command but not when actually flying.
I think this is unnecessary because always show the “swoosh” subtitle when activating elytra is a bit weird (sometimes we can accidentally activate the elytra while jumping) , maybe only show this subtitle when your speed >20m/s is better