Okay, so I was double wrong. Just installed rainloop app and found the rainloop address book totally independent from contacts app and nextcloud users. Would have at least expected an optional integration of the contacts app here.
But indeed you can sync the rainloop address book with en external carddav und thus with your nextcloud carddav/contacts app.
When create some test contacts with rainloop, they are shown in the list directly. Typing some latters into the search field and pressing enter shows just the contacts with matching string, whether its in the name or email. So works quite well for me.
And now when I compose an email, I can see your perhaps confusion:
- The auto completion for address field when composing an email does also include contacts from contact app, perhaps also nextcloud user accounts.
- But inside the rainloop address book/contacts (by pressing the button besides “New message”), you just see the contacts, that are really part of the rainloop app, so are created within, gathered through received emails or synced with “external” carddav server, configured within the app.
Because I don’t see the contacts app icon on your screenshot: Where do the contacts shown up on writing an email come from? Are they users of the same nextcloud instance and might be your rainloop indeed still empty of “own” contacts, or ARE they indeed contacts created/gathered within the rainloop app and you face an graphical issue here?
In the latter case: Are there some errors shown in nextcloud log or browser console?