**SOLVED**
While the main client appears to work fine, the browser extension is useless on my system - nothing happens when clicking the icon in a username field, and when using the right-click menu to fill username and password, again, nothing happens. The database is unlocked and detected as connected, and browser integration is enabled, so I'm at a loss as to what to do to fix it.

edit: autotype works, but this is unrelated to the extension.

edit2: Somehow, it's all working now, one particular site was fixed by removing its subdomain in its entry, but I've no idea why all the others started working - one of the restarts or extension reinstalls must have done the trick