The Alexa alerts only work with person detection so far, so yes you’d need a valid CamPlus subscription on each camera you want to use to trigger Alexa routines. I don’t know the story with the new live view feature - it just came out this month.
Note that you can do a lot with native Wyze app rules without using Alexa.
In the past renaming a camera has helped with stubborn Alexa issues so you could try that if you want… Also reinstalling the Wyze skill, telling Alexa to discover, reinstalling the app, etc.
Edit: just noticed this thread: