In order to force safari history syncing between your iPad/iPhone and Mac, you will need to first enable the “debug” menu.. This is not to be confused with the “Develop” menu, which you can enable in Safari’s settings. Make sure you have also selected “safari” within your iCloud account settings on all devices you want to sync.

1st, close safari completely with Command-Q (or whatever your preferred method is)

2nd, go to ‘System Preferences > Security & Privacy > Privacy > Full Disk Access’ and add Terminal.

3rd, within Terminal, execute ‘defaults write com.apple.Safari IncludeInternalDebugMenu 1′ (without the quotes’

4th, launch Safari, and on the newly created “Debug” menu, choose ‘Sync iCloud History’

You should know see your synced history between that Mac and your iOS devices!