I have Opera on 2 desktops at home and 1 laptop on the road - I'm on the road. Sync has worked very well in the past. But today, when I looked for a recent bookmark (set at home on desktop), it wasn't there. So, I started down a lengthy rabbit hole that appears to have no end. I've been through many screens, some of which asked about my 'passphrase'- I have no clue if I have one or what it is. I tried to reset it. More rabbit hole (meaning a meander about but get nowhere good).

Starting all over (new profile, etc.) doesn't appeal. I really want to use the profile I have. I will be home tonight and can see what the situation is on the desktops.

One of the many screens visited was: https://www.sync.opera.com. It tells me: "You have no sync data stored.
Sign in to Opera to start syncing, and access your bookmarks and other browser data from all your devices."

But I am signed in to Opera and that page gives me no option to sign in again.