Bookmarks not being synced from macOS to iOS I'm on High Sierra 10.13.6 on a MBP 13" 2015  and iOS 11.4.1 on an iPhone 7.
I have been using iCloud for several years and have never had any trouble with it. 

However a few days ago, I noticed the Bookmarks and Favorites weren't syncing from my iPhone to my MBP, and when clicking on "edit" on iPhone's Safari Bookmarks I constantly got the message:


  Bookmarks are being synced. Please add the bookmarks once syncing has completed


I have tried setting off Safari iCloud sync on both devices, also deleted permanently bookmarks from both of them, deleted the file "Bookmarks.plist" from ~/Library/Safari and also deleted the file "com.apple.SafariCloudHistoryPushAgent.plist" from ~/Library/Preferences. 

All that with no luck. The deleted bookmarks keep showing up on iOS Safari when turning back on Safari iCloud Sync on iPhone.
Found a solution in case anyone is interested:

On icloud.com on "Preferences" under "Advanced" there's a link to "Restore Bookmarks", after permanently deleting every bookmark on there, I got iOS and macOS Safaris to be in sync again.

Note that even after solving the issue, iOS is taking longer than ever to sync Safari Bookmarks, it used to be almost instant and now takes more than 5 minutes.