1Password MAS seems to have broken Safari extensions

Hi all,

Since updating to the MAS 7.8.7 version, none of my 1Password extensions are working in Safari – resulting in my having to copy and paste out of the (full) app.
Running Safari 14.1.2, on macOS 11.5.1 (Big Sur).

When clicking on the 1P extension icon in the toolbar, nothing happens. Restarting Safari does nothing, neither does deselecting/reselecting the extension in Safari preferences.
Similarly, when clicking into a username or password field in Safari, clicking on the 1P icon to unlock, so that it can fill in the details, does nothing.
Triggering the shortcut key to autocomplete my details, also does nothing.

Anyone else seeing this?

1Password Version: 7.8.7
Extension Version: 7.8.7
OS Version: 11.5.1