I installed the iOS 13 GM on iPhone XS Max, as well as the iPad OS 13 Beta 8 on a iPad Pro 2018. I have Messages syncing to iCloud. Currently Messages are syncing between the two iOS devices, however my Mojave machines don't seem to be syncing with any inbound or outbound messages coming in or out of other devices. When sending messages directly from the Mojave machine messages are being sent out but the response messages are not coming back to the Mojave systems, but are coming back to the iDevices.
iPhone XS Max (ios 13GM)
iPad Pro 12inch 2018 (iPad OS 13 Beta 8)
iMac Pro (Mojave 10.14.6)
MacBook Pro 15 (Mojave 10.14.6) - Not syncing with Messages
MacBook Pro 13 (Mojave 10.14.6) - Not syncing with Messages
Is anyone else running into this issue? Do the Mac systems need to be upgraded to Catalina in order to be in parity with the iOS 13 systems?
No issues here. Mojave here - iPhone XS Max was running 13 all the way up to 13.1 b3. Now running 13 GM. In and out, no issues.