The Chrome extension for 1 Password stopped working on me about a week ago. First in the office on my iMac and then at home on my MacBook Air. I ignored it for awhile but then tried reinstalling the plugin a few times before realising that wasn't the problem. I'm not sure if there was a new update to Sophos lately but the problem was that Sophos was not allowing connections to locahost, which the extension needs in order to work properly.
Simple fix. I'm leaving this post up as breadcrumbs for the next person.