Unable to auto-fill username after updating from 1password7 to 1password8

I have the same (or similar) problem on a Galaxy S8.

With 1Password 7, most of the time when clicking on a username or password field it would give me a drop-down to pick a login (or pop up an overlay to search for it if it didn't find a matching one). When that failed (occasionally) to happen you could long-press on the field and select "auto-fill" there to trigger the same thing.

However, with 1Password 8 there doesn't appear to be any indication that it's even been invoked. Clicking on the username and password field just brings up the keyboard. There's never any drop down to select an login from or trigger the search overlay, and long-pressing the fields no longer presents an "auto-fill" option (it does give me an option to paste, so I can still at least copy/paste from the main 1Password app, but that's pretty inconvenient).

I've tried disabling and re-enabling 1Password in the device's autofill service settings, and have also tried various combinations of the settings in 1Password's autofill settings in the app.