Intercom not working on Apple watch.
My wife's Apple watch doesn't display an intercom icon, and when you use the Siri intercom functionality it displays a message "to do that turn on intercom setting on home app setting" when the setting is enabled everywhere I can think of.
The icon is available on the IPhone the watch is paired with and the intercom function works fine using the icon and Siri.
iPhone and watch software is up to date.