For my address books, I have a Google contact account, an ownCloud CardDAV account from a DAV groupware resource and a Personal Contacts account set up. When typing a name or E-mail address in the To: field of an E-mail, addresses are auto-completed from both my Google address book and Personal Contacts address book, but never from my CardDAV address book. Reproducible: Always
how I can configure it for testing it ?
I've done more testing, and it looks like I was mistaken - Tor was interfering with the reliability of my CardDAV address book's syncing.