iMac 2020 not showing same messages in iMessage as other devices

I have a new iMac 2020 logged into iCloud with the same id as all my other devices. My iMac 2013, MacBook Pro, iPad and iPhone all show the same list of conversations and messages in iMessage. The new Mac only shows five of those conversations and only accepts new messages from those 5 people, notifications from my Dr, USPS, anything other than those 5 do not show up. iMessage settings are identical to my other iMac, all devices are on the latest macOS, iOS, iPadOS

How do I get it to show the same messages as the rest of my devices?