Universal Clipboard not working from iPhone to Mac

I'm experiencing the same intermittent Universal Clipboard issue between my iPhone and MacBook, both running the latest available versions of iOS and macOS.

In my case, the problem is specifically iPhone → Mac. Copying from Mac → iPhone works correctly, and Safari Handoff also works. The issue affects all apps, not just one particular application.

I investigated this using macOS logs from sharingd and useractivityd.

When Universal Clipboard was failing:

• The Mac was still receiving Handoff advertisements from the iPhone.
• I saw SFActivityAdvertiserOptionFlagCopyPasteKey = 0 in an advertisement.
• I did not see the usual remote pasteboard availability or data-fetch events during my failed copy/paste attempts.

When Universal Clipboard was working:

• Received pboard available advertisement
• SFActivityAdvertiserOptionFlagCopyPasteKey = 1
• Sending client xpc remote available update: YES
• Requesting data from remote device
• PBData came with stream request
• Hide progress ... with fail: NO

Temporary fix that worked for me:

Running the following command in macOS Terminal immediately restored iPhone → Mac clipboard sharing:

killall sharingd useractivityd

macOS normally restarts these background services automatically. This can briefly interrupt Continuity features.

This suggests a possible issue with the state of the macOS Continuity services, although I haven't confirmed the root cause or identified which process is responsible.

I've also noticed that toggling Bluetooth on the iPhone can sometimes temporarily restore the functionality.

Has anyone found a permanent fix?

Restarting these services works as a workaround, but I'd really like to understand why Universal Clipboard stops detecting the iPhone's clipboard in the first place.