This broke recently, likely when they changed the voice codecs for match-making.
How to bind CS:GO Radio Commands to Keys? I have no problem viewing teammates' messages.
However, sometimes they give you a hard time trying to do so.
Players can use up to three chat wheels and all commands are completely customizable.
In this case anything higher than 0 will "unhide" it.
It might sound unbelievable, but it is 100% true.