"Unable to save item" - can't save login info for any web site

Jack,
Performed the steps above in Chrome (and, just to try again, in Edge). After removing/reinstalling the extension and restarting the browser, the 1Password extension icon appears in the browser with a small lock icon on it. Clicking on the 1Password icon brings up a dialog with a button labeled "Open 1Password". Clicking on that button doesn't do anything (won't log me in to 1Password in the browser extension). Trying to log in to a web site doesn't get any response from 1Password to add the new info to my vault (obviously, since I'm not logged in in the browser). I got the same result in Edge as in Chrome (replaced extension, restarted, won't log me in).

Extra credit fun: installed the 1Password app on my iPhone. Attempted to log in after scanning the QR code on my Emergency Kit sheet, and the app won't log in. Just gives me a red banner and a message to enter my account details, which are all filled in after scanning the QR and manually entering my password.

This is, unfortunately, not a good start for my 1Password experience.