If I have Uconnect enabled as above, and my phone set to "Show Message Notifications", then every time a new text message comes in, the truck will announce the new message and then read the entire thing. I personally do NOT want this, so I have the "Show Message Notifications" in my phone disabled. Because of this, the ONLY way I know there is a new message is if I'm on the CarPlay screen on Uconnect, and I just happen to look down and see a small green dot on top of the phone icon. In fact, my phone and my watch will not alert me either, as the truck takes priority. I wish there was some way to have the truck just simply alert that a message came in, as it did years ago - but Apple CarPlay does not work that way. Frankly this sucks, but it's an Apple thing, not Ram.
If you have the Uconnect settings enabled, and your iPhone is set up as you've shown, then when you get a new text message, it should be read out-loud as soon as it comes in.
If you're still dead in the water, then I hope someone else can help. I'm out of ideas.