There are two Live interfaces. The extension was made to work on https://www.chess.com/live
It probably won't work on https://www.chess.com/play/online which is the newer interface.
Will the 'old' interface go away at some stage? What happens then?
I think Chess.com should add move announcing as a built in feature rather than relying on an extension that could easily become outdated
Here an explanation of what lead to the previous post.
When one opens an ongoing game by clicking a game under Today / Playing Now, the URL is like
https://www.chess.com/play/online?action=follow&member=KNVB
The URL then redirects to the actual game, like
https://www.chess.com/game/live/16453487763
This opens the new interface, and the voice extension does not announce the moves here.
When one clicks now Play / Live Chess, the URL changes to like
https://www.chess.com/live#g=16453487763
This is as I understand the old interface, and here the voice extension is working.