That rule looks sound. However, it has been my experience that the Beta Chromecast integration doesn’t work consistently. Because of this, I have been using the Alexa Echo Speaks community integration instead for notifications.
I have two that I use for announcements..They have been pretty reliable for me. Are you able to send speak commands from the device page?
I would also recommend using the polling setting from the app page or some kind of rule to initialize them on a schedule....there is also a chrome cast helper community app available too.
Thanks all. Reset them all, deleted and recreated the rules and messed with the volume settings and seem to have them working decently. The Google hub still isn’t working but I can troubleshoot and/or do without it.
Now for my next trick, is there anyway to change the TTS voice?
I noticed a difference when setting up a hub (Google Home Hub or Google display) for TTS notifications when compared to setting up a regular Google speaker. The hub (or display) seems to need the setting called "Delay before speaking, seconds" set to at least 1. When set to none, you hear the tone that precedes a TTS message but never hear the message. When set to 1 it seems to work.