Had this problem, started windows media player going in the background. Yep, at 40% sound shut off. Went back and song was still playing, but no sound. After a little while sound started back up. Went back into Minecraft, which had to reload, but it reloaded with sound.
The workaround might be minimizing Minecraft then getting it to reload. Might be needed each time Minecraft is started. A sound source might be needed to tell when ready.
Worked a second time after closing out Minecraft and starting it all the way back up again. Replicated.
I have been having the issue, just tested it and yep, still there.
Steps to reproduce: Start an item smelting in the furnace. Deselect the furnace. Wait until it is done smelting the item and not lit up anymore. Open furnace, arrow icon is partially full and stopped.
Xbox Series S, v1.21.71