I've been using 1P since … v3 maybe. As early as everything was out on iOS too.
I've had 1P 7 on iOS for quite some time now, along MacOS 1P 6. And it worked quite well.
Just upgraded the MacOS to 7.
My vault got … upgraded ? … there. And I cannot seem to have my two 1P 7 to sync now.
I deleted both apps, reinstalled. I followed the sync troubleshooting (turning sync off, reseting iCloud data, restarted sync), did not work.
I completely remove the app on iOS, reinstalled, and now, at startup, iCloud shows "no vault were found in iCloud", while MacOS shows confirmation of the sync with the time.
I'm a developper, and went to check what's in my MobileDocs (iCloud), and I see two entries:
Could that maybe be the source?
1Password Version: MacOS 1P 7.3.1, iOS 1P 7.3.3
Extension Version: Not Provided
OS Version: MacOS 10.14.5, iOS 12.3.1
Sync Type: iCloud