MacOS Screen Sharing - Not working between M1 iMac and Intel iMac

We have followed all the suggested tips and help ideas for settings on the Apple Forums and Apple help sites.

Screen Sharing appears to make a connection and indeed tells the remote Mac that accepted the sharing invite that my iMac is controlling the other screen. However, no screen ever shows up on my "controlling" iMac despite the message on the remote iMac. These iMacs are connected over the internet and not on the same local network.

Any ideas or experience? Thanks.