Installed "1Password for Safari" extension missing in Safari Preferences

Since a couple of days I have no 1Password suggestions in Safari. In fact, the "1Password for Safari" icon is missing in the toolbar and (worse) the extension itself is not listed in the Safari Preferences. In an attempt to resolve this I removed "/Applications/1Password for Safari.App", re-downloaded it from the App Store, and ran it. It told me to open Safari Preferences, but it's still missing in action there...

I'm using Safari Version 15.3 (16612.4.9.1.8, 16612).

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1Password Version: 80600050 (Nightly)
Extension Version: 2.2.3
OS Version: macOS Big Sur 11.6.4