Safari 6.5.2 and Chrome 4.6.2.90 browser extensions not working at all

macOS Sierra 10.12.2

1Password 6.5.2

Safari 10.0.2 (12602.3.12.0.1)
Safari extension 6.5.2

Chrome 55.0.2883.95 (64-bit)
Chrome extension 4.6.2.90

Neither the browser bar button nor the keyboard shortcut works in either browser—literally nothing happens when I click on either.

When in a browser and I click on the 1Password mini in the menubar, it offers to install the extension in that browser—despite it clearly being installed and the button being present in the browser (although nonfunctional).

I have installed, uninstalled, and reinstalled the extension and restarted Safari both after and inbetween.

I saw a similar (I think) post here:

https://discussions.agilebits.com/discussion/72955/new-update-6-5-2-doesnt-autofill-any-websites-nor-does-the-tool-bar-work-im-using-safari-9-1-1?

I will answer the questions posted there, in the hopes of saving time:

[What are the exact steps you normally take to have 1Password fill sign-in forms on websites?]

Click on the button in browser bar.

[What happens if you click on the URL field of a Login item in the main 1Password app?]

It takes me to the site, but doesn't fill the password info.

[What happens if you open a website by choosing a Login item from the 1Password extension in the browser?]

Can't, since extension button unresponsive

[What happens if you go to a website first, and then choose the matching Login item from the 1Password extension?]

Can't, since extension button unresponsive

[When using the extension, do you click the 1Password icon in your browser's toolbar, or do you use the ⌘\ keyboard shortcut?]

Usually the former, but neither works at all.

1Password Version: 6.5.2
Extension Version: 10.0.2 and 6.5.2
OS Version: macOS 10.12.2
Sync Type: Not Provided