Thanks for your response. Yes, the box is properly checked. I did a little more testing and the Mac’s a visible until they go to sleep. I can go to one of them and wiggle the mouse causing the login screen to pop up then that Mac will show up in the connection screen of the other machines. It will stay visible until it goes back to sleep.
I should mention that all of them have been upgraded to the free version 7.7.4.
They are all Intel based Mac’s of various ages and are running macOS Big Sur, Catalina and Monterey.