iPhone iCloud Keychain not syncing

So recently my iPhone stopped syncing my keychain information from my Macbook.

I've tried updating my iOS on my iPhone to the latest & OS on my Macbook to the latest, but that didn't help.

Nothing from apple support pages (https://support.apple.com/en-sg/HT203783) helped too.

I was almost going to use another password manager to store my passwords that could sync. I was starting to use google to save my new passwords.

Then I chanced upon this thread (https://discussions.apple.com/thread/8187366). Specifically this post:

"I did have some luck removing one device from my iCloud. In this case, I removed my MacBook Pro because I didn't want to re-do all my Apple Pay cards on my iPhone. But, when I did this, it triggered some kind of re-authorization of all my existing devices. So I basically had to re-enter my password on all my devices, and once that was done my iCloud passwords started synchronizing again. I don't know if it will stay that way, but we'll see."

I didn't have any spare device that I could remove from my iCloud, so I added a spare iPhone I had at home to my existing iCloud by signing into my iCloud using that spare iPhone.

And that did the trick! I can ditch my plans to use another password manager.

Hope that helps.