/stopsound command does not work

With spiders in earshot, I type the following command:

/stopsound @s mob.spider.step

ER:  the spider step sound should no longer play for me

AR:  message displays "Stopped all sounds for <playerName>"  All sounds still play.

 

Resources:

https://minecraft.gamepedia.com/Sounds.json/Bedrock_Edition_values

https://minecraft.gamepedia.com/Commands/stopsound#Target_selectors