Missing passwords on both Mac and iPhone after upgrading to iOS 18

Upgraded my iphone to iOS 18 which was when they introduced the Passwords app, looks like at least half of my passwords were lost in the transition.

I open keychain (as I used to) and some of the old entries are there but when I click 'view password' they are just blank.

Keychain is enabled in iCloud settings for both mac and iOS.

I don't have a time machine backup.

I'm on iOS 18.01 and OSX 14.4.1

Anyone else had this problem? I know they are likely lost forever and I should just start rebuilding but my god this is a pain, has really put me off Apple.

[Re-Titled by Moderator]