I'm unable to sign in to iMessage in my Mojave VM. Other iCloud options like Calendar and Contacts seem OK. Error is:An error occurred during activation. Try again. Trying again results in the same error over and over. I often see graphics problems in Safari windows that have tabs. Tabs flicker and are almost unreadable. Maps still doesn't show any maps.
That article doesn't apply to my situation. When I ran the Mojave VM (under Parallels desktop for mac version 14 running on El Capitan), Parallels tools automatically installed. I tried Facetime after that, and it worked with the built-in camera on my Mid 2012 Macbook pro, but not the isight Firewire camera. Both work fine in the native El Capitan.