Keychain not syncing across devices via iCloud - iPhone, iPad, Mac

I use keychain on several Apple devices. Since a while the sync doesn't work across devices.

If I add a new password or change an existing one, it only gets stored on the device itself, and not to iCloud/the other devices. Apple Support couldn't help to solve the problem. They already knew about the issue, but couldn't help to fix it.

The only recommendation support gave is to not use the old workaround (to turn off iCloud sync of keychain on all devices + enable it again) as it can lead to data loss.

Did anyone experience the same issue and can share how to resolve it?

Apple Team, why is there no button to trigger a sync manually? This doesn't seem too complicated.

You can read the timestamps and see which is the most up-to-date PW. You even can keep the old PW in addition to the newly synced ones, to ensure you don't cause any data loss.