I got a new Macbook and set is up from time machine backup - now some keychain items are missing

I got a new Macbook and set is up from time machine backup. Some keychain items (webpage passwords at least) are now missing in the new computer. Luckily my previous Macbook (still running Yosemite) is still working so I have access to the missing passwords, but it's not ideal solution.

Also I noticed that the at least some of the missing passwords are not found in my iPhone either. Maybe this is iCloud syncing issue with Keychain?

I have no idea where to start solving the issue, any help?