Recently I've had two issues:
- Mojave Universal Clipboard stopped working between Mojave and iOS 15.4.1
- Mojave notes iCloud synced but always showed a spinning activity icon
I found that I could make Universal Clipboard work again by creating or editing a note on my iPhone or on Mojave. Once that synced then UC worked until I rebooted.
If Universal Clipboard isn't working first reboot your devices and confirm connection to WiFi with Bluetooth enabled. Then try toggling Handoff off/on on both devices. Then try:
- Changing my Mojave location DNS settings from Cloudflare (1.1.1.1) to Google (8.8.8.8). (Based on this post)
- Toggling Notes iCloud off then on again (restores notes)
Now the spinning is gone, and UC seems to be working.
Update 5/15/2022: UC is back to not working unless I create a note that's synced between iOS and Mojave. Notes doesn't show the skinny activity icon. So this is an open problem.
Update 8/30/2023
Continuity has worked since May 2022 on my Mojave machine, but I'm now switching to a 2023 M2 Air running Monterey. And, of course, the Universal Clipboard didn't work again.
A few hours later my devices notified me that iCloud services would not be available until I reauthenticated. That tedious and annoying process requires entering the iCloud and device passwords; I think it creates a new token/password behind the scenes. After going through this continuity worked again. Signing in and out of iCloud is a common workaround for Continuity issues, I suspect it speeds up regeneration of the new token/password.
It would be nice if Apple improved this process.
PS. Typical things to check when it doesn't work: bluetooth on, devices on same WiFi, etc.
