Probably not a technical bug but something the developers might consider a design bug.

Issue: No sound plays when a player equips armor (including elytra) from within their inventory screen via dragging the mouse or when shift clicking but it does play a sound when armor is equipped from the hotbar by scrolling to it and right clicking to equip.

Just in case you have to ask, here's why it's an issue:

1. It breaks game immersion since a sizeable number of players are probably like myself in that we forget that it makes sound in the first place since we never use the hotbar for armor. It is slower than shift clicking and hotbars are rarely freed up enough to begin with.
2. It is a potential issue in pvp servers, especially now with the subtitles option.
3. It is simply an inconsistent design.