@80f08b97 I recently moved 10+ years of 1Password data into iCloud password, but did it all at once. I followed https://simonbs.dev/posts/moving-from-1password-to-icloud-keychain/ . I actually did this twice for ~ 900 passwords, since the first time I realized how much 1Password has been putting in non-standard fields that don't get exported to CSV. I recommend first going thru your 1P data, moving everything from custom fields to the notes field, then exporting from 1Password to CSV, then importing to iCloud keychain on your Mac. 

 @9342d4ca thanks for the guidance!