Safari tabs sync on two macs and an iPhone does not work Syncing using iCloud with 2 macs and an iPhone does not work. I use iCloud to sync safari, and my MacBook is perfectly synchronized with my iPhone. 
The problem is that my iMac is not synchronized at all.  When I add some website to a reading list on the MacBook, it does not appear in the iMac. 

I tried to uncheck and recheck the Safari checkbox in iCloud on all of my devices, but it didn't help. 
Does anyone know how to fix this?

I am running the latest Mojave(10.14.6) on both Macs, and iOS 12 on my iPhone.

Update

As @ankii suggested, I've tried to remove all bookmarks from the iPhone and the iMac, and resync. Now the bookmarks are syncing between these devices, but the open tabs are not. On my iPhone I can see the open tabs from the MacBook but not from the iMac. On the iMac I see no open tabs from none of my other devices.

I also tried to follow this answer MacOS Safari iCloud tabs stop working randomly after some time but it didn't help.
It's a radical way  to solve it, but that's how I did it. Export the bookmarks.HTML  using File menu in Safari. Then start cleaning up the bookmarks, reading list and favourites from all the devices. On Macs it's easy to do using "Edit bookmarks" and right-click on an item on reading list to clear all. 


How to clear ALL items from Safari&#39;s reading list?


After all devices, and iCloud have no bookmarks, reading list etc, check the sync by adding a test bookmark. If it does, then import the HTML file. If not, try uncheck/check Safari sync in System Preferences. 

Also, this is not a verified remark, but Safari stopped syncing the moment I made bookmark folders on my Mac. I had to use them without folders.