Since the extension works flawlessly in all other browsers I've chalked it up to Safari extensions being a pain.
But yes the Safari 1Password extension constantly shits The bed.
The publishing process for Safari extensions is painful, but otherwise it's not meaningfully different from Chromium extensions and there's no good reason for it to work worse in Safari.
The publishing process for Safari extensions is painful, but otherwise it's not meaningfully different from Chromium extensions and there's no good reason for it to work worse in Safari.