This issue can be resolved

Lo and behold, after all these years, the latest iPadOS updates have resolved this issue for me too. I reopened this defect before these fixes, and now I feel that it can be closed. Hurrah!

After updating my iPad to iOS 6.1.1, sound works normally. 

Just testet the workflow as described by tsobczynski with 1.19.50 on iPadOS 16.1.1 (20B101).

With this environment setting, the sound Problem isn't reproducible. (It was, however, before I updated the OS as well as the app).

Suggested solution for iPad: run all possible updates.

I’ve had the same exact issue as well, for the last several small updates. I always have to close Minecraft entirely then reopen the game to get sounds to work again. I’m running IOS 15.7 on an ipad pro. Current Minecraft Version is affected as were prior versions; Minecraft is showing up-to-date on version 1.19.41.

Please add 1.19.40 to the affected versions. I just confirmed it.

1. Start Minecraft, trigger some in-game sound such as tapping on a chest.
2. Press the iPad sleep/wake button to put the iPad to sleep.
3. Press the iPad sleep/wake button again and unlock as needed.
4. Observe that Minecraft resumes as expected.
5. Trigger the same in-game sound, e.g. by tapping a chest.

Expected outcome: the associated sound is played

Actual outcome: No sound is played, and Minecraft remains silent indefinitely.

Audio stops playing in-game until the app is force-quit and restarted. This happens whenever the Minecraft app leaves the foreground. For example, accidentally tapping an iOS notification and immediately four-finger-swiping back to the game, or accidentally pressing sleep/wake or having the device sleep due to idle time. The game comes back to the foreground without issue, but no more audio will play until the app is force-quit.

Still affects 1.19.31 on my iPad Pro running iOS 15.7. Any time I go back to my Home Screen and then switch back to MC I have to restart MC to get the sound to come back. 

Still affects 1.19.31 on my iPad pro

as a Workaround I usually just force-quit Minecraft every time I start playing 

On my iPad you swipe up from the bottom of the screen to show all open apps then swipe up on the Minecraft tile to force quit it. It takes so long to reopen anyway, this doesn’t add much.

Happened upon a temp fix- go back to where it says play, settings and marketplace, click marketplace and minimize it, then click the app from “home” of your device, not the app bar (iPad). Works on iPhone too.